A CONVENIENT PROCEDURE FOR THE TRANSFORMATION OF ALCOHOLS TO OLEFINS AND ALKYL CHLORIDES
作者:Hsing-Jang Liu、Wing Hong Chan、Sing Ping Lee
DOI:10.1246/cl.1978.923
日期:1978.9.5
Treatment of 1° alcohols with N,N-dimethylphosphoramidic dichloride in refluxing 1,2-dimethoxyethane gave the corresponding chlorides. Upon similar treatment, 3° alcohols underwent dehydration giving olefinic products, whereas 2° alcohols afforded olefins or chlorides as predominant products.
Aspects of the Reduction of Double Bonds Using Cob (I)alamin as Catalys
作者:Albert Fischli
DOI:10.1002/hlca.19820650839
日期:1982.12.15
The olefinic system in 3β-methoxy-4-cholesten-6 a-ol (2) is reduced using cob (I)alamin (1(I); see Scheme 1) as catalyst, aqueous acetic acid as solvent and metallic zinc as electron source (cf. Schemes 2 and 3). Experimental evidence for an attack of 1(I) on both faces of the double bond is presented. By the same catalyst (1 R)-10, 10-dimethyl-2-pinene- 10-carbonitrile (9) is first transformed to
Synthesis of 5.ALPHA.-cholestan-6-one derivatives with some substituents at the C-1, C-2, or C-3 position.
作者:SUGURU TAKATSUTO、NOBUO IKEKAWA
DOI:10.1248/cpb.35.986
日期:——
In order to investigate the regioselectivity of Baeyer-Villiger oxidation, thirty 5α-cholestan-6- one derivatives with various substituents (methyl, hydrogen, acetoxymethyl, methoxy, acetyloxy, benzoyloxy, trifluoroacetyloxy, p-toluenesulfonyloxy) at the C-1, C-2, or C-3 position were synthesized from cholesterol. The 6-oxo functional group of 5α-cholestan-6-one derivatives was introduced via hydroboration. The 3β-derivatives were readily obtained by using the native 3β- hydroxyl group of cholesterol. The 3α-isomers were obtained by inversion of the configuration of the 3β-tosylate 24 with tetra-n-butylammonium acetate in refluxing 2-butanone. The 2β-isomers were derived from the 2-ene 43 by bromohydrination, LiAlH4 reduction, and esterification. The 2β- to 2α-hydroxyl group inversion was achieved by Birch reduction of the 2-oxo steroid 51. The 1α-derivatives were derived from the known 6β-acetoxy- 1 α-hydroxy-5α-cholest-2-ene (57).