Abstract: A compound is represented as Formula I, a tautomer thereof, a stereoisomer thereof, or a pharmaceutically acceptable salt thereof. Compounds of Formula I are inhibitors of N-acylethanolamine hydrolyzing acid amidase (NAAA). The present technology is directed to compounds, compositions, and methods to inhibit N-acylethanolamine hydrolyzing acid amidase and to treat N-acylethanolamine hydrolyzing acid amidase mediated conditions in a subject.

Abstract: The present invention relates to the synthesis of intermediates which are useful in TTX synthesis and to the preparation thereof.

Abstract: Compounds of formula (I) (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: Compounds of formula (I): (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: Compounds of formula (I): (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: Compounds of formula (I) (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: The present invention provides 2-azetidinone derivatives, or pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof, comprising formula (I): wherein the substituents are as herein defined. The compounds possess cholesterol absorption inhibitory activity and are accordingly of value in the treatment of disease states associated with hyperlipidaemic conditions.

Abstract: Compounds of formula (I) (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: The invention is directed to novel azetidinones selected from 2-(S)-[4-(((2-(Dimethylamino)ethyl)ethylamino)carbonyl)phenoxy]-3,3-diethyl-N-[1-(R)-(4-(trifluoromethoxy)phenyl)butyl]-4-oxo-1-azetidin ecarboxamide, 2-(S)-[4-(((2-(Dimethylamino)ethyl)ethylamino)carbonyl)phenoxy]-3,3-diethyl-N-[1-(R)-(4-(trifluoromethyl)phenyl)butyl]-4-oxo-1-azetidinecarboxamide, and analogs thereof, and pharmaceutically acceptable salts thereof, and their use in the treatment of diseases associated with an excess of elastase, including emphysema, bronchial inflammation, chronic bronchitis, cystic fibrosis, acute respiratory distress syndrome, rheumatoid arthritis, osteoarthritis; glomerulonephritis, spondylitis, lupus, psoriasis, atherosclerosis, sepsis, septicemia, shock, myocardial infarction, reperfusion injury, and periodontitis.

Abstract: The application relates to novel 2-azetidinone derivatives of formula (I) and pharmaceutically acceptable salts, solvates and prodrugs thereof. The compounds are cholesterol absorption inhibitors and are useful in the treatment of hyperlipidaemic conditions, including atherosclerosis, Alzheimers' disease and cholesterol associated tumours. The application also relates to pharmaceutical formulations comprising such compounds and to processes for their preparation.

Abstract: The invention relates to novel 2-azetidinone derivatives of formula (I) and to pharmaceutically acceptable salts, solvates and prodrugs thereof. The compounds are cholesterol absorption inhibitors, useful in the treatment of hyperlipidaemic conditions. The invention also relates to processes for their manufacture and to pharmaceutical compositions containing them.

Abstract: Compounds of formula (I): (wherein variable groups are as defined within) pharmaceutically acceptable salts, solvates, solvates of such salts and prodrugs thereof and their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia are described. Processes for their manufacture and pharmaceutical compositions containing them are also described.

Abstract: The invention relates to compounds of formula (I) and pharmaceutically acceptable salts, solvates, and prodrugs thereof, and to their use as cholesterol absorption inhibitors for the treatment of hyperlipidaemia. The invention also relates to processes for their manufacture and pharmaceutical compositions containing them.

Abstract: The invention relates to 2-azetidinone derivatives of formula (I), including pharmaceutically acceptable salts, solvates and prodrugs thereof. The compounds inhibit cholesterol absorption and are useful in the treatment of hyperlipidaemic conditions. The invention also relates to processes for their manufacture and to pharmaceutical compositions containing them.

Abstract: The present invention relates to a stereoselective synthesis of novel ?-lactam dimers as useful precursors for the preparation of paclitaxel, docetaxel, and analogues thereof. More particularly, the new ?-lactams are prepared from readily available and enantiomerically pure chiral auxiliaries. The ?-lactams are then reacted with a suitably protected taxane to produce diastereomerically enriched side chain-bearing taxanes. Finally, the chiral auxiliary is cleaved and protecting groups are removed to provide the desired taxane.

Abstract: The invention relates to a chemical genus of 4-biphenyl-1-phenylazetidin-2-ones useful in the treatment of hypercholesterolemia and other disorders. The compounds have the general formula I: Pharmaceutical compositions and methods for treating cholesterol- and lipid-associated diseases are also disclosed.

Abstract: The present invention discloses the usage of Poly-3-hydroxybutyrates P(3HB) in preparation of ?-lactam compounds and the method for the preparation of ?-lactam compounds of formula (I) using Poly-3-hydroxybutyrates P(3HB) as followed: wherein: R is R1, R2, R3 are lower linear or branched C1-C4 alkyl. It is convenient to synthesize the said compound of formula (I) with the present method. Compared with the previous ones, the present method has less steps and higher yields.

Abstract: 2-azetidinone derivatives and pharmaceutical compositions containing them. The compounds are useful in the treatment of hyperlipidemic conditions, atherosclerosis, Alzheimers' disease and cholesterol associated tumours.

Abstract: Compounds are provided which have the structure Wherein A, B, C, D, m, Y, Ra, Rc, Rd, and Rd? are as described herein, and which are useful as inhibitors of tryptase, thrombin, trypsin, Factor Xa, Factor VIIa, Factor XIa, and urokinase-type plasminogen activator and may be employed in preventing and/or treating asthma, chronic asthma, allergic rhinitis, and thrombotic disorders.

Abstract: The present invention provides methods for identifying (3-amino-2-oxo-azetidin-1-yl) acetic acid derivatives with anti-PBP2a activity. The method involves the selection of RNA biocatalysts that promote the formation of (3-amino-2-oxo-azetidin-1-yl) acetic acid derivatives with anti-PBP2a activity from component reactants. The invention also provides novel (3-amino-2-oxo-azetidin-1-yl) acetic acid derivatives with anti-PBP2a activity identified by these methods. The invention also provides RNA biocatalysts that are capable of catalyzing the formation of (3-amino-2-oxo-azetidin-1-yl) acetic acid derivatives from component reactants.

Abstract: A process for the preparation of 3-cyclic-ether-substituted cephalosporins of formula I wherein the group CO2R1 is a carboxylic acid or a carboxylate salt and R2 has the formula: wherein A1 and A2 have the meanings given in the specification by reacting compound of formula II: wherein R2 is as defined above and R3 is para-nitrobenzyl or allyl with a compound R2 L wherein R2 is as defined above; and L is di-(C1-6 alkyl)phosphorothioate in the presence of a solvent and a base.

Abstract: Novel ?-lactam compounds represented by the following formula (I) or pharmaceutically acceptable salts thereof which are useful as serum cholesterol-lowering agents: (I) wherein A1, A3 and A4 represent each hydrogen, halogen C1-5 alkyl, C1-5 alkoxy, —COOR1, a group represented by the following general formula (b): (b) wherein R1 represents hydrogen or C1-5 alkyl, or a group represented by the following general formula (a): (a) wherein R2 represents —CH2OH, —CH2OC(O)—R1 or —CO2—R1; R3 represents —OH or —OC(O)—R1; R4 represents —(CH2)kR5(CH2)1- wherein K and 1 are each 0 or an integer of 1 or above provided k+1 is an integer of not more than 10; and R5 represents a single bond, —CH?CH—, —OCH2—, carbonyl or —CH(OH)—; provided that at least one of A1, A3 and A4 is a group represented by the above formula (a); A2 represents C1-5 alkyl, C1-5 alkoxy, C1-5 alkenyl, C1-5 hydroxyalkyl or C1-5 carbonylalkyl; and n, p, q and r are each an integer of 0, 1 or 2.

Abstract: The present discovery consists in new thiazole-substituted ?-lactams of general formula (I), as well as the method for their preparation. R1, R2, R3, R4, R5, R6, R7, and R8 are, independently from each other, a hydrogen atom, a halogen, a hydroxy, amino, nitro, or thiol group, an optionally substituted alkyl, heteroalkyl, aryl, aralkyl, cycloalkyl, cycloaralkyl, heterocycloalkyl, heteroaralkyl, or heteroaryl rest.

Abstract: Taxane derivatives having an amino substituted C13 side chain.

Abstract: 1 Compounds of formula (I) wherein Z is —CH2SR and R represents hydrogen or —COCH3, are useful as metalloproteinase inhibitors, especially as inhibitors of MMP 13.

Abstract: This invention relates to substituted azetidin-2-ones and to pharmaceutical compositions containing such compounds. Their use in medicine as inhibitors of cysteine proteases, particularly the cathepsins is also described. The invention includes a compound of formula (I), Y represents —C(O)— or —S(O2)—; R represents an allyl (ie CH2═CHCH2—) group or a radical. R1 represents —OCOR5, —OR5, —SR5, —S(O)R5, or —S(O)2R5; R2 represents a radical. R3 represents —OR5 or R5; or a pharmaceutically acceptable salt, hydrate or solvate thereof.

Abstract: A process for preparing N-acyl, N-sulfonyl and N-phosphoryl substituted isoserine esters in which a metal alkoxide is reacted with a &bgr;-lactam.

Abstract: A simple and efficient method is proposed for the preparation of a &bgr;-lactam compound such as 1-phenyl-4-ethoxy-2-azetidinone which can be produced by mixing an isocyanate compound such as phenyl isocyanate and a vinyl ether compound such as ethyl vinyl ether and heating the mixture at a moderate temperature under a superatmospheric pressure of up to 12000 atmospheres.

Abstract: Novel &bgr;-lactams finding utility as intermediates in the preparation of sidechain-bearing taxes such as tall and tall derivatives. The present invention also relates to novel methods of coupling &bgr;-lactams to form such sidechain-bearing taxes, and to novel sidechain-bearing taxes.

Abstract: A compound of formula 1: wherein Y is S or O; R1 is C1-6 alkyl; (C0-6 alkyl)aryl; (C0-6 alkyl)Het; or R1 is an amino acid analog or dipeptide analog of the formula: wherein R2 is H, C1-10 alkyl; or an amide or ester group; A is C6-10 aryl, Het or CH—R3 wherein R3 is C1-6 alkyl or (C0-4 alkyl)aryl; and Z is H, C1-6 alkyl, or an acyl; R4 is hydrogen, lower alkyl, methoxy, ethoxy, or benzyloxy; and R5 is alkyl, cycloalkyl, carboxyl group; an aryl; Het or Het(lower alkyl); or R4 and R5 together with the nitrogen atom to which they are attached form a nitrogen containing ring optionally substituted with phenyl or C(O)OCH2-phenyl, said phenyl ring optionally mono- or di-substituted with among others C(O)OR7 wherein R7 is lower alkyl or phenyl(lower alkyl); or a therapeutically acceptable acid addition salt thereof which compounds are useful in the treatment of HCMV infections.

Abstract: This invention relates to methods for treating diseases or disorders mediated by lipid inflammatory mediators, arachidonic acid, its metabolites and/or platelet activating factor (PAF), which method comprises administration to a mammal in need thereof of an effective Coenzyme A independent transacylase (CoA-IT) inhibiting amount of a triphenylmethylazetidinone. This invention also relates to a method of treating or reducing inflammation in a mammal in need thereof, which comprises administering to said mammal an effective amount of a triphenylmethylazetidinone.

Abstract: Processes for the preparation of [S-(R,S)]-N-[1,3-benzodioxol-5-yl)butyl]-3,3-diethyl-2[4-[4-methyl-1-piperazinyl)carbonyl]phenoxy]-4-oxo-l-azetidine carboxamide, a useful inhibitor of human leukocyte elastase (HLE), are described. The process including (a) contacting a compound of formula (II): with a compound of formula (III): in a first polar solvent system in the presence of an aqueous base and a phase transfer catalyst, to form the title compound, or a salt form thereof.

Abstract: A process for the preparation of a taxane derivative of the formula in which R2 represents an RO—, RS— or RR′N— in which R represents an unsubstituted or substituted straight chain or branched alkyl, alkenyl or alkynyl, or cycloalkyl, saturated heterocyclic, cycloalkenyl, unsaturated heterocyclic, aryl or heterocyclic aromatic; R′ is a hydrogen or R defined above; R and R′ can be connected to form together with the nitrogen a cyclic structure; Y is oxygen or sulfur; R3 represents an unsubstituted or substituted straight chain or branched alkyl, alkenyl or alkynyl radical, an unsubstituted or substituted cycloalkyl, cycloalkenyl or an unsubstituted or substituted aryl; which comprises reacting a &bgr;-lactam of the formula in which R311 represents a radical R3 defined above or a protected R3 whenever R3 includes one or more active hydrogens; with a baccatin III derivative of the formula: in which M is an alkali metal

Abstract: Azetidinone derivatives of formula (I) in which R.sup.1 and R.sup.2, which may be the same or different, is each selected from hydrogen or C.sub.(1-8) alkyl; R.sup.3 is C.sub.(1-8) alkyl or C.sub.(3-8) cycloalkyl each of which may be optionally substituted; X is a linker group; Y is an aryl group; and n is 0, 1 or 2; and excluding benzyl (4-methylthio-2-oxo-azetidin-1-yl)acetate are inhibitors of the enzyme Lp PLA2 and are of use in therapy, in particular treating atherosclerosis.

Abstract: The present invention provides novel cis-N-iminomethyl-3,4-disubstituted-2-azetidinones, and their use in the preparation of N-acyl-2-azetidinones, intermediates in the semi-synthesis of taxol and taxol derivatives.

Abstract: A method of preparing intermediates for carbapenem antibiotics characterized by treating a N-deprotected acetoxy conpound of the formula: ##STR1## in the presence of a Lewis acid or a silylating agent to yeild an intermediate; and cyclizing the intermediate in the presence of rhodium (II) acetate to form a bicyclic ketoester.

Abstract: Compounds of formula (I) in which R.sup.1 and R.sup.2, which may be the same or different, is each selected from hydrogen, halogen or C.sub.(1-8) alkyl; R.sup.3 is aryl or aryl C.sub.(1-4) alkyl which may be optionally substituted; X is a linker group; Y is an optionally substituted aryl group; and n is 0, 1 or 2; are inhibitors of the enzyme Lp-PLA.sub.2 and thereof of use in treating atherosclerosis.

Abstract: New substituted azetidinones of the general Formula (I) which have been found to be potent elastase inhibitors and thereby useful anti-inflammatory and antidegenerative agents are described, wherein n is

Abstract: In accordance with the present invention, there are provided 4-substituted-3-(2-amino-2-cycloalkyl methyl)-acetamido azetidin-2-one derivatives of the formula: ##STR1## wherein n is 1, 2 or 3; in which R.sub.1, R.sub.2 and R.sub.3 are as defined herein, and salts thereof, which exhibit excellent cysteine proteinase inhibitory activity and which can be used for treatment of different diseases such as muscular dystrophy, myocardial infarction, bone resorption, arthritis, cancer metastasis, pulmonary emphysema, septic shock, cerebral ischemia, memory function, Alzheimer and cataract, malaria, glomerular basement membrane degradation, bacterial infection, inflammatory diseases, parasitic infections, and viral infections.

Abstract: Novel .beta.-lactam monomers bearing various functional groups are prepared. The novel .beta.-lactam monomers can be joined into oligomeric compounds such as via preferred phosphate linkages including phosphodiester and phosphorothioate linkages. Useful functional groups include nucleobases as well as polar groups, hydrophobic groups, ionic groups, aromatic groups and/or groups that participate in hydrogen bonding. The oligomeric compounds are useful as diagnostic and research reagents.

Abstract: 3-Bromo- and 3,3-dibromo-4-oxo-1-azetidines of the formula I ##STR1## wherein R.sub.1 is hydrogen or bromo,R.sub.2 is hydrogen or bromo,R.sub.3 is hydrogen, ##STR2## wherein R.sub.4 is hydrogen, methyl, benzyl or some other protective group,R.sub.5 is hydrogen, alkyl, alkylaryl, a heterocyclic ring,Y is a halo atom,X is a halo atom, alkoxy group, nitroxy group are provided along with processes for the preparation thereof and the use thereof.

Abstract: The present invention relates to the process for the preparation of the substituted azetidinone having the formula: ##STR1## comprising a convergent synthesis wherein the azetidinone portion of the molecule is coupled to the lower benzodioxole portion via a base catalyzed addition to an isocyanate.

Abstract: This invention provides a process for preparing azetidinones useful as intermediates in the synthesis of penems and as hypocholesterolemic agents, particularly for azetidinones substituted in the C-3 and C-4 positions and optionally substituted at the ring nitrogen, comprising reacting a .beta.-(substituted-amino)amide, a .beta.-(substituted-amino)acid ester, or a .beta.-(substituted-amino)thiolcarbonic acid ester with a silylating agent and a cyclizing agent.

Abstract: Substituted azetidinone hypocholesterolemic agents of the formula ##STR1## or a pharmaceutically acceptable salt thereof, wherein: Ar.sup.1 is aryl or R.sup.3 -substituted aryl;Ar.sup.2 is aryl or R.sup.4 -substituted aryl;R.sup.1 is selected from the group consisting of--(CH.sub.2).sub.q --, wherein q is 2, 3, 4, 5 or 6;--(CH.sub.2).sub.e --Z--(CH.sub.2).sub.r --, wherein Z is --O--, --C(O)--, phenylene, --NR.sup.10 -- or --S(O).sub.0-2 --, e is 0-5 and r is 0-5, provided that the sum of e and r is 1-6;--(C.sub.2 --C.sub.6 alkenylene)--; and--(CH.sub.2).sub.f --V--(CH.sub.2).sub.g --, wherein V is C.sub.3 -C.sub.6 cycloalkylene, f is 1-5 and g is 0-5, provided that the sum of f and g is 1-6;R.sup.2 is --(lower alkylene)--COR.sup.5 or --(CH.dbd.CH)--COR.sup.5 ;R.sup.3 and R.sup.4 are independently selected from the group consisting of 1-3 substituents independently selected from the group consisting of lower alkyl, --OR.sup.6, --O(CO)R.sup.6, --O(CO)OR.sup.9, --O(CH.sub.2).sub.1-5 OR.sup.6, --O(CO)NR.sup.6 R.

Abstract: Sulfur-substituted azetidinone hypocholesterolemic agents of the formula ##STR1## or a pharmaceutically acceptable salt thereof, wherein: Ar.sup.1 is aryl, R.sup.10 -substituted aryl or heteroaryl;Ar.sup.2 is aryl or R.sup.4 -substituted aryl;Ar.sup.3 is aryl or R.sup.5 -substituted aryl;X and Y are --CH.sub.2 --, --CH(lower alkyl)-- or --C(dilower alkyl)--;R is --OR.sup.6, --O(CO)R.sup.6, --O(CO)OR.sup.9 or --O(CO)NR.sup.6 R.sup.7 ; R.sup.1 is hydrogen, lower alkyl or aryl; or R and R.sup.1 together are .dbd.O;q is 0 or 1; r is 0, 1 or 2; m and n are 0-5; provided that the sum of m, n and q is 1-5;R.sup.4 is selected from lower alkyl, --OR.sup.6, --O(CO)R.sup.6, --O(CO)OR.sup.9, --O(CH.sub.2).sub.1-5 OR.sup.6, --O(CO)NR.sup.6 R.sup.7, --NR.sup.6 R.sup.7, --NR.sup.6 (CO)R.sup.7, --NR.sup.6 (CO)OR.sup.9, --NR.sup.6 (CO)NR.sup.7 R.sup.8, --NR.sup.6 SO.sub.2 R.sup.9, --COOR.sup.6, --CONR.sup.6 R.sup.7, --COR.sup.6, --SO.sub.2 NR.sup.6 R.sup.7, S(O).sub.0-2 R.sup.9, --O(CH.sub.2).sub.1-10 --COOR.sup.6, --O(CH.

Abstract: Sulfur-substituted azetidinone hypocholesterolemic agents of the formula ##STR1## or a pharmaceutically acceptable salt thereof, wherein: Ar.sup.1 is aryl or R.sup.10 -substituted aryl;Ar.sup.2 is aryl or R.sup.4 -substituted aryl;Ar.sup.3 is aryl or R.sup.5 -substituted aryl;X and Y are --CH.sub.2 --, --CH(lower alkyl)-- or --C(dilower alkyl)--;R is --OR.sup.6, --O(CO)R.sup.6, --O(CO)OR.sup.9 or --O(CO)NR.sup.6 R.sup.7 ; R.sup.1 is hydrogen, lower alkyl or aryl; or R and R.sup.1 together are .dbd.O;q is 0 or 1; r is 0, 1 or 2; m and n are 0-5; provided that the sum of m, n and q is 1-5;R.sup.4 is selected from lower alkyl, --OR.sup.6, --O(CO)R.sup.6, --O(CO)OR.sup.9, --O(CH.sub.2).sub.1-5 OR.sup.6, --O(CO)NR.sup.6 R.sup.7, --NR.sup.6 R.sup.7, --NR.sup.6 (CO)R.sup.7, --NR.sup.6 (CO)OR.sup.9, --NR.sup.6 (CO)NR.sup.7 R.sup.8, --NR.sup.6 SO.sub.2 R.sup.9, --COOR.sup.6, --CONR.sup.6 R.sup.7, --COR.sup.6, --SO.sup.2 NR.sup.6 R.sup.7, S(O).sub.0-2 R.sup.9, --O(CH.sub.2).sub.1-10 --COOR.sup.6, --O(CH.sub.2).sub.

Abstract: New substituted azetidinones of the general Formula (I) which have been found to be potent elastase inhibitors and thereby useful anti-inflammatory and antidegenerative agents are described. ##STR1## wherein R.sub.4 is (a) ##STR2## or (b) ##STR3## where R.sub.x is carboxy C.sub.1-6 alkyl, benzyloxycarbonylC.sub.1-3 alkyl, or t-butoxycarbonylC.sub.1-3 alkyl,whereinQ is a covalent bond or ##STR4## wherein R.sub.5 and R.sub.6 are each individually C.sub.1-3 alkyl or hydrogen,Y is ##STR5## or a covalent bond.

Abstract: A derivative of 3-(7'-oxo-1'-aza-4'-oxabicyclo[3.2.0 ]hept-3'-yl)propionic acid represented by the formula ##STR1## wherein R.sub.1 is a hydrogen atom, a lower alkyl group optionally having one or more cycloalkyl groups, a lower acyl group, a benzoyl group optionally having one or more substituents or a benzyl group optionally having one or more substituents, R.sub.2 is a hydrogen atom or a carboxyl-protecting group, R.sub.3 is a hydroxyl group, an azido group, a benzenesulfonyloxy group optionally having one or more substituents, a lower alkylsulfonyloxy group optionally having one or more substituents, a tri-substituted silyloxy group or an amino group optionally having one or more substituents, provided that when R.sub.1 and R.sub.2 are hydrogen atoms, R.sub.3 is not an amino group, and a salt thereof.

Abstract: A process for preparing a .beta.-lactam compound of the formula (I): ##STR1## which comprises cyclization of an azetidinone derivative of the formula: ##STR2## is provided in which R.sup.1 is hydrogen, alkyl which is optionally substituted, or amino which is optionally substituted; R.sup.2 is a carboxy-protecting group; and X is alkylene which is optionally intervened by --O-- or --S--, and/or which is optionally substituted; and R.sup.3 is aryl which is optionally substituted.

Abstract: A .beta.-lactam of the formula: ##STR1## wherein R.sub.1 is aryl, substituted aryl, alkyl, alkenyl, or alkynyl; R.sub.2 is hydrogen, alkyl, acyl, acetal, ethoxyethyl, or other hydroxyl protecting group; and R.sub.3 is aryl, substituted aryl, alkyl, alkenyl, or alkynyl; and the enantiomers and diastereomers thereof.