Stereoselective acetalization of 1,3-alkanediols by l-menthone: application to the resolution of racemic 1,3-alkanediols and to the determination of the absolute configuration of enantiomeric 1,3-alkanediols
摘要:
A general and reliable method for the resolution of racemic 1,3-alkanediols, which involves their conversion into diastereomeric spiroacetals derived from l-menthone, is described. Thus, the reaction of the bis-O-trimethylsilyl derivatives of racemic 1,3-alkanediols with l-menthone in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate affords the diastereomeric spiroacetals 3 and 4. The two can be readily separated by silica gel column chromatography. Hydrolysis of each diastereomer under acidic conditions liberates the corresponding enantiomerically pure diol. An empirically derived correlation of configuration and H-1 NMR chemical shifts for spiroacetals 3 and 4 has been developed which is rationalized based on long-range effects due to the magnetic anisotropy inherent to the menthane ring in a rigid spiroacetal conformation. The method described here should be widely applicable to the determination of the absolute configuration of various 1,3-alkanediols.
Changing places: Intramolecular B(pin)/H exchange took place in the presence of a platinum–phosphane catalyst, giving synthetically useful cis‐β‐methyl‐substituted alkenylboronatesstereoselectively (see scheme; B(pin)=4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl).
Iron(III) Chloride/Phenylsilane‐Mediated Cascade Reaction of Allyl Alcohols with Maleimides: Synthesis of Poly‐Substituted γ‐Butyrolactones
作者:Hua Zhang、Xiao‐Yu Zhan、Xu‐Ling Chen、Lei Tang、Shuai He、Zhi‐Chuan Shi、Yu Wang、Ji‐Yu Wang
DOI:10.1002/adsc.201900843
日期:2019.11.5
A iron‐catalyzed free radical cascade reaction of allyl alcohols with N‐substituted maleimides for accessing poly‐substituted γ‐butyrolactones has been developed. In this protocol, various allyl alcohols can open N‐substituted maleimide rings to form allyl ester intermediates, and the allyl ester intermediates can be converted into an allyl ester alkyl radicals and undergo intramolecular free radical
[EN] ALDEHYDES AS PERFUMING INGREDIENTS<br/>[FR] ALDÉHYDES EN TANT QU'INGRÉDIENTS DE PARFUM
申请人:FIRMENICH & CIE
公开号:WO2013117433A1
公开(公告)日:2013-08-15
The present invention relates to an aldehyde of formula (I) in the form of any one of its stereoisomers or a mixture thereof, and wherein each dotted line, independently from each other, represents a single or double bond; n is 0 or 1; R1 represents a hydrogen atom or a methyl group; R2 represents a hydrogen atom or a methyl or ethyl group; and R3, which is a substituent in any of the positions 2 to 6 of the cyclic moiety, represents a hydrogen atom or a methyl or ethyl group, or a CH2 group bridging positions 3 and 6; and its use as perfuming ingredient, for instance to impart odor notes of the aldehyde, lily of the valley type.
Highly diastereoselective hydrosilylations of allylic alcohols
作者:Mark G. McLaughlin、Matthew J. Cook
DOI:10.1039/c4cc00138a
日期:——
The highly syn-selective hydrosilylation of allylic alcohols was developed which, following oxidation, provided 1,3 alcohols containing two contiguous stereocentres.