Abstract: The present invention relates to dihydropyran derivatives, processes for preparing, and processes of using the derivatives. The derivatives are prepared by condensation of lithium dienolate of prenal with an aldehyde or a ketone.The pyran derivative prepared from .beta.-ionylideneacetaldehyde when treated in the presence of a catalyst directly forms retinal.

Abstract: The (R) or (S) isomer of acetorphan or N-/2-acetylthiomethyl)-1-oxo-3-phenylpropyl/(S) alanine methyl ester is prepared by splitting of racemic acetylthio-2-benzylpropanoic acid by reaction with ephedrin, separation of the enantiomeric salt obtained, then freeing of the acid and coupling with the corresponding amino acid ester. The obtained preparations possess remarkable therapeutic activities and can notably be used as drugs.

Abstract: The present invention relates to dihydropyran derivatives, processes for preparing, and processes of using the derivatives. The derivatives are prepared by condensation of lithium dienolate of prenal with an aldehyde or a ketone.The pyran derivative prepared from .beta.-ionylideneacetaldehyde when treated in the presence of a catalyst directly forms retinal.

Abstract: The present invention relates to a process for preparing halo acetals of ethylenic aldehydes by reaction of a halogen cation with enamine followed by a hydrolysis and reaction with an alcohol, a glycol or an orthoformate. These halo acetals are used as intermediate for the synthesis of vitamins A and E.It also relates to a new compound of formula (IV), ##STR1## to a process for preparing it from halo acetals of ethylenic aldehydes by reaction with triethyl phosphate, and to its use for the preparation of retinal by reaction with .beta.-ionylideneacetaldehyde.

Abstract: The (R) or (S) isomer of acetorphan or N-12-acetylthiomethyl-1-oxo-3-phenyl propyl/(S) alanine methyl ester is prepared by splitting of racemic 3-acetylthio-2-benzyl propanoic acid by reaction with ephedrin, separation of the enantiomeric salt obtained, then freeing of the acid and coupling with the corresponding amino acid ester. The obtained preparations possess remarkable therapeutic activities and can notably be used as drugs.

Abstract: New intermediates and processes for the preparation of vitamins A and E, which are the acetals of 5,6-dihalo-3-methyl-3-hydroxyhexanal or of 6-halo-3-hydroxy-3-methyl-5-hexenal or 3-methyl-3-hydroxy-5-hexenal, as well as processes for making the intermediates. After dehydrohalogenation and dehydration these intermediates are condensed directly with .beta.-ionone or with 2-methyl-2-heptene-6-one to synthesize vitamins A and E respectively.

Abstract: 6-halo-3-methyl-1-trialkylsilyloxy-1,3,5-hexatriene, useful as an intermediate in the preparation of terpene compounds, is prepared by reaction of a 6-halohexadienal with a halo-silane in the presence of a tertiary amine.

Abstract: 1,3,5-Nonatriene derivatives of formula: ##STR1## in which R.sub.1 and R.sub.2, together with the carbon atom to which they are linked, form a carbonyl group, or each of R.sub.1 and R.sub.2 denotes alkoxy or R.sub.1 and R.sub.2 together form an alkylenedioxy radical, which may be made by reaction of a butadiene derivative of formula: ##STR2## in which R is alkyl or phenyl, with a butanal ketoacetal of 10 formula: ##STR3## followed by reaction of the product with a halomethyltriphenylphosphonium halide, are useful intermediates e.g. for the production of phytol.

Abstract: Polyene aldehydes are made by reaction of a carbonyl compound of formula: ##STR1## in which R denotes a hydrocarbon radical and R' denotes hydrogen or alkyl, with a metal derivative of a halogen compound of formula: ##STR2## in which X denotes halogen (preferably bromine), R.sub.3 is alkyl, and either R.sub.1 denotes hydrogen and R.sub.2 denotes an alkoxy radical indentical with OR.sub.3 or R.sub.1 and R.sub.2 together form a bond, followed by hydrolysis of the product obtained.

Abstract: Polyene aldehydes are made by reaction of a carbonyl compound of formula: ##STR1## in which R denotes a hydrocarbon radical and R' denotes hydrogen or alkyl, with a metal derivative of a halogen compound of formula: ##STR2## in which X denotes halogen (preferably bromine), R.sub.3 is alkyl, and either R.sub.1 denotes hydrogen and R.sub.2 denotes an alkoxy radical identical with OR.sub.3 or R.sub.1 and R.sub.2 together form a bond, followed by hydrolysis of the product obtained.

Abstract: A chiral .alpha.-amino acid having a hydrogen substituent in a position alpha to the carboxylic function thereof is prepared by subjecting a corresponding optical antipode with a chiral amino acid to a strong base whereby the proton in a position alpha to the carboxylic function is removed and thereafter reacting the resulting product with a chiral protonation agent.