Abstract: A process for preparing an optically active 4-hydroxy-2-cyclopentenone of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom or a methyl group, R.sub.2 is an alkyl group, an alkenyl group or an alkynyl group and the asterisk (*) indicates an asymmetric configuration, which comprises subjecting an optically active 4-cyclopentenone-alcohol of the formula: ##STR2## wherein R.sub.1 and R.sub.2 are each as defined above, the asterisk (*) indicates an asymmetric configuration and the substituents R.sub.1 and R.sub.2 take a cis-configuration to rearrangement while maintaining the original steric configuration.

Abstract: A process for preparing an optically active 2-substituted or unsubstituted-4-hydroxy-2-cyclopentenone of the formula: ##STR1## wherein R is a hydrogen atom, an allyl group or a propargyl group, which comprises reacting the corresponding 2-substituted or unsubstituted-4-hydroxy-2-cyclopentenone of the formula: ##STR2## wherein R is defined above with a lactone chosen from (1R,5S)-6,6-dimethyl-4-hydroxy-3-oxabicyc lo[3.1.0]hexan-2-one or (1S,5R)-6,6-dimethyl-4-hydroxy-3-oxabicyclo[3.1.0]hexan-2-one in a molar ratio of 1.5 - 2:1 in the presence of p-toluenesulfonic acid or benzenesulfonic acid in the coexistence of an organic solvent under elimination of water as an azeotropic mixture with the organic solvent to obtain a reaction mixture comprising (1R,5S)-6,6-dimethyl-3-oxa-4(R)-[1(R)-4-oxo-2-substituted or unsubstituted-2-cyclopentenyloxy]bicyclo[3.1.0]hexan-2-one or (1S,5R)-6,6-dimethyl-3-oxa-4(S)-[1(S)-4-oxo-2-substituted or unsubstituted-2-cyclopentenyloxy]bicyclo[3.1.

Abstract: By hydrolyzing a sulfonic acid ester or a nitric acid ester of an optically active 4-hydroxy-2-cyclopentenone, the steric inversion of the hydroxyl group at the 4-position of the cyclopentenone mentioned above is effected.4-hydroxy-2-cyclopentenone is useful as a raw material of prostaglandins (natural substance is an (R)-substance) having stimulative action to uterine muscle and vasodilator action. For instance, 4(S)-hydroxy-2-cyclopentenone can be configurationally inverted to R-isomer. Accordingly, this method is extremely meaningful in the synthesis of prostaglandins.

Abstract: A process for preparing cyclopentenone derivatives of the formula: ##STR1## wherein R.sup.1 is hydrogen, lower alkyl or lower alkenyl, R.sup.2 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, cycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted ar(lower)alkyl and A is the residue of a nucleophilic agent from which a hydrogen atom is excluded, which comprises reacting a 3-hydroxy-4-cyclopentenone compound of the formula: ##STR2## wherein R.sup.1 and R.sup.2 are each as defined above with a nucleophilic agent of the formulaA--H (III)wherein A is as defined above.The cyclopentenone derivatives of the formula (I) are useful as pharmaceuticals, agricultural chemicals, perfumes and as intermediates for the preparation of agricultural chemicals, pharmaceuticals and perfumes.

Abstract: A process for producing a compound of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom, an alkyl group or an alkenyl group and R.sub.2 is an alkyl group, an alkenyl group or an alkynyl group, which comprises treating a compound of the formula: ##STR2## wherein R.sub.1 and R.sub.2 are each as defined above and R is a hydrogen atom or a lower alkyl group in the presence of an acidic substance and water.

Abstract: A method for producing an optically active 2,2-dimethylcyclopropanecarboxylic acid useful as an intermediate for dehydropeptidase I inhibitors, medicines and agricultural chemicals, which comprises reacting an optically active diphenylethylamine represented by the formula, ##STR1## wherein R.sub.1 and R.sub.2 are each a hydrogen atom or a lower alkyl group, with 2,2-dimethylcyclopropanecarboxylic acid in a solvent to achieve the optical purification of said acid.

Abstract: A method for producing 2-cyclopentenones represented by the formula, ##STR1## wherein R represents an alkyl, alkenyl, cycloalkyl, substituted or non-substituted aryl or aralkyl group, which comprises heating 4-cyclopentenones represented by the formula, ##STR2## wherein R has the same meaning as above, in the presence of 1,8-diaza-bicyclo[5,4,0]undecene or its organic acid salt.The 2-cyclopentenones are useful as an intermediate for perfumes, medicines and agricultural chemicals.

Abstract: 2-Cyclopentenone esters of the formula: ##STR1## wherein R.sup.1 is hydrogen, lower alkyl or lower alkenyl, R.sup.2 is lower alkyl, lower alkenyl, lower alkynyl, or cycloalkyl, cycloalkenyl or substituted or unsubstituted aryl and R.sup.3 is hydrogen or lower alkyl are prepared in high yields by reacting the corresponding racemic or optically active 4-cyclopentenone of the formula: ##STR2## wherein R.sup.1 and R.sup.2 are each as defined above and R.sup.3 is hydrogen or acyl with at least one lower aliphatic carboxylic acid and/or metal or amine salts thereof.

Abstract: A 4-cyclopentenone of the formula: ##STR1## wherein R is a lower alkyl group, a lower alkenyl group or a lower alkynyl group and R' is a hydroxyl group or an aliphatic acyloxy group, provided that in case of the dl-form, R' is not a hydroxyl group and also that the substituent R at the 2-position and the methyl group at the 3-position take a cis-configuration in the dl-, d- or l-form.

Abstract: A novel process for preparing 2-cyclopentenones of the formula: ##STR1## wherein R.sub.1 is hydrogen, alkyl or alkenyl and R.sub.2 is alkyl, alkenyl, alkynyl, cycloalkyl, aryl or aralkyl, which comprises esterifying a mixture of a 3-hydroxy-4-cyclopentenone of the formula: ##STR2## wherein R.sub.1 and R.sub.2 are each as defined above and a 4-hydroxy-2-cyclopentenone of the formulas: ##STR3## wherein R.sub.1 and R.sub.2 are each as defined above with an aliphatic carboxylic acid to give a mixture of the 4-hydroxy-2-cyclopentenone (III) and the cyclopentenone ester of the formula: ##STR4## wherein R.sub.1 and R.sub.2 are each as defined above and R is hydrogen or C.sub.1 -C.sub.4 alkyl and subjecting the resulting mixture to reduction.

Abstract: A process for preparing an aromatic aldehyde represented by the following general formula: ##STR1## wherein R.sub.1 and R.sub.2 each represents a hydrogen atom or a lower alkyl group or R.sub.1 and R.sub.2 may jointly form an alkylene group, provided that R.sub.1 and R.sub.2 do not represent a hydrogen atom at the same time.

Abstract: Bisphenoxy carboxylic acid derivatives useful as an antiarteriosclerosis agent with good absorbability and low toxicity, which are novel compounds represented by the general formula, ##STR1## wherein R.sub.1 and R.sub.2 represent hydrogen atoms or lower alkyl groups and A preresents ##STR2## (wherein in case R.sub.3 is a hydrogen atom, R.sub.4 represents an amino-lower-alkyl group, an N-lower-alkylaminoalkyl group, a heterocyclic group, or a heterocyclic group-substituted alkyl group; or R.sub.3 and R.sub.4 may join through an intermediary hetero atom to form a heterocyclic group and if said hetero atom is a nitrogen atom, this nitrogen atom can bear a lower alkyl group as a substituent) or ##STR3## (wherein R.sub.5 represents a hydrogen atom, a hydroxyalkyl group or a derivative thereof, and R.sub.6 represents a hydroxyalkyl group or a heterocyclic group; or R.sub.5 and R.sub.

Abstract: Novel anti-atherosclerosis agents having the formula, ##STR1## wherein R is hydrogen or lower alkyl, n and m each signify an integer of 4 - 6, and A is hydrogen or a group of the formula, ##STR2## WHEREIN R and m have the same meanings as defined above. These compounds are produced, for example, by reacting a bisphenolic compound of the formula, ##STR3## with chloroform and a ketone compound of the formula, ##STR4## in the presence of an alkali. Alternatively, they are produced by reacting the bisphenolic compound with .alpha.-halogeno- or .alpha.-hydroxycarboxylic acid derivative of the formula, ##STR5## wherein R and m have the same meanings as defined above, and X is halogen or hydroxyl.

Abstract: Bisphenoxy carboxylic acid derivatives useful as an antiarteriosclerosis agent with good absorbability and low toxicity, which are novel compounds represented by the general formula, ##STR1## wherein R.sub.1 and R.sub.2 represent hydrogen atoms or lower alkyl groups and A represents ##STR2## (wherein in case R.sub.3 is a hydrogen atom, R.sub.4 represents an amino-lower-alkyl group, an N-lower-alkylaminoalkyl group, a heterocyclic group, or a heterocyclic group-substituted alkyl group; or R.sub.3 and R.sub.4 may join through an intermediary hetero atom to form a heterocyclic group and if said hetero atom is a nitrogen atom, this nitrogen atom can bear a lower alkyl group as a substituent) or ##STR3## (wherein R.sub.5 represents a hydrogen atom, a hydroxyalkyl group or a derivative thereof, and R.sub.6 represents a hydroxyalkyl group or a heterocyclic group; or R.sub.5 and R.sub.

Abstract: Novel compounds having the formula, ##SPC1##Wherein R.sub.1, R.sub.2 and R.sub.3 are each independently hydrogen or a C.sub.1 -C.sub.4 alkyl; n is an integer of 4-6; and Y is hydrogen or a group of the formula ##EQU1## wherein R.sub.1, R.sub.2 and R.sub.3 are as defined above. These compounds are produced, for example, by reacting a bisphenolic compound of the formula, ##SPC2##With chloroform and a ketone compound of the formula,R.sub.1 -- CO -- R.sub.2in the presence of an alkali. Alternatively, they are produced by reacting the bisphenolic compound with .alpha.-halogeno- or .alpha.-hydroxycarboxylic acid derivative of the formula, ##EQU2## wherein R.sub.1, R.sub.2, and R.sub.3 are as defined above, and X is a halogen or hydroxyl. The novel compounds are anti-atherosclerosis agents useful for lowering elevated levels of cholesterol or lipids.