Abstract: A cyclopentenecarboxamide derivative represented by the formula (I): and a method for preparing the cyclopentencarboxamide derivative. A bicycloamide derivative represented by the formula (II): and a method for preparing the bicycloamide derivative.

Abstract: A cyclopentenecarboxamide derivative represented by the formula (I): and a method for preparing the cyclopentencarboxamide derivative. A bicycloamide derivative represented by the formula (II): and a method for preparing the bicycloamide derivative.

Abstract: A cyclopentenecarboxamide derivative represented by the formula (I): 1

Abstract: A cyclopentenecarboxamide derivative represented by the formula (I): ##STR1## and a method for preparing the cyclopentencarboxamide derivative. A bicycloamide derivative represented by the formula (II): ##STR2## and a method for preparing the bicycloamide derivative.

Abstract: A cyclopentenecarboxamide derivative represented by the formula (I): ##STR1## and a method for preparing the cyclopentencarboxamide derivative. A bicycloamide derivative represented by the formula (II): ##STR2## and a method for preparing the bicycloamide derivative.

Abstract: There are provided novel and optically active 2,2-dimethyl-1,3-dioxin-4-ones which are useful as starting materials for physiologically active compounds, functional materials or the like. Provided are optically active 5,6-epoxyhexanoic acid esters and novel optically active 6-substituted tetrahydropyran-2-one derivatives.

Abstract: There are provided novel and optically active 2,2-dimethyl-1,3-dioxin-4-ones which are useful as starting materials for physiologically active compounds, functional materials or the like. Furthermore, a method for preparing an optically active compound comprises reacting a racemic 1,3-dioxin-4-one with vinylacetate in the presence of lipase to resolve the racemic compound into optically active compound represented by the formula (3) ##STR1## and an optically active compound represented by the formula (4) ##STR2## which is an antipode of the compound represented by the formula (3).

Abstract: The present invention relates to a process for producing cyclobutane derivatives represented by general formula (28): ##STR1## (wherein R represents a substituent; R.sub.2 represents an electron attracting group and Nu represents a substituent corresponding to nucleophilic reagent), by reacting a compound represented by general formula (27): ##STR2## (wherein R has the same significance as defined above and R.sub.1 represents an electron attracting group) with nucleophilic reagents Nu.sup..crclbar. in a solvent.The compounds of formula (28) are useful as intermediates for synthesis of, for example, 9-[2,3-bis(hydroxymethyl)cyclobutan-1-yl]guanine which is expected to be useful as an antiviral agent.

Abstract: 3-Oxo-2-azabicyclohexane derivatives represented by the general formula: ##STR1## wherein R.sub.1 represents an optically active menthoxy group or an optically active 1-phenylethoxy group when R.sub.2 and R.sub.3 are combined to form a bond; when R.sub.3 is a hydrogen atom, R.sub.1 and R.sub.2 are combined to form an oxo group or, R.sub.2 is a hydrogen atom and R.sub.1 is a hydroxy group or a lower alkanoyloxy group. The 3-oxo-2-azabicyclohexane derivatives are novel compounds useful as intermediates for antibacterial agents.

Abstract: A process for producing 3-oxo-6-formyl-2-oxabicyclo[3.3.0]-6-octene useful as an intermediate for producing prostaglandins, via a few steps from raw materials which can be relatively easily prepared. The process comprises subjecting 2,2-dimethyl-1,3-dioxin-4-one and cis-2-cyclopenten-1,4-diol to addition reaction in a solvent, preferably under a photo-irradiation, removing the solvent from the reaction mixture, adding water to the resulting adducts and reacting the resulting mixture on heating.

Abstract: A process for producing 1,3-dioxin-4-one derivatives having a lower alkyl group at 2-position and useful as a starting raw material for prostaglandins, with a high yield is provided, which process comprises reacting formyl Meldrum's acid with a lower aliphatic carbonyl compound of 2 to 4 carbon atoms in a solvent containing the carbonyl compound at 100.degree. to 120.degree. C., while portionwise adding the acid into the solvent, the total quantity of the acid added being 0.2 mol or less per liter of the solvent.

Abstract: Steroid derivatives represented by the formula ##STR1## wherein R.sup.1 and R.sup.2 are as defined hereunder which is useful for easily producing a wide variety of active vitamin D, and a process for preparing the same are disclosed.

Abstract: 3.alpha.,6.alpha.-Dihydroxy-5.beta.-cholestan-24-one or its derivative represented by the formula ##STR1## wherein R is as defined hereunder which is a useful intermediate for the production of an active vitamin D, and a process for preparing the compound of the formula are disclosed.

Abstract: A steroid derivative represented by the formula ##STR1## wherein R is as defined hereunder and a process for preparing the same are disclosed. The derivative is an intermediate for the production of various useful compounds.

Abstract: 1.alpha.,25-dihydroxycholecalciferol is prepared by reacting 1,5,7-trien-3.beta.,25-diol with a 1,2,4-triazoline-dione derivative represented by the formula: ##STR1## wherein R represents an alkyl group or an aryl or substituted-aryl group; reacting the resulting 1,4-cyclic adduct represented by the general formula ##STR2## wherein R is as defined above, with a peroxide to form a 1.alpha.,2.alpha.-epoxide compound represented by the general formula ##STR3## wherein R is as defined above, reducing the so formed compound with a metal hydride to form cholesta-5,7-diene-1.alpha.,3.beta.,25-triol, irradiating the so formed compound with ultraviolet rays to form 1.alpha.,25-dihydroxyprevitamin D.sub.3, isomerizing the so formed previtamin D.sub.3, and recovering 1.alpha.,25-dihydroxycholecalciferol.

Abstract: 1.alpha.,2.alpha.-Dihydroxycholecaliciferol having improved vitamin D activities and a process for preparing the same are disclosed.