Convergent synthesis of conjugated 1,2-disubstituted E-allylic alcohols from two aldehydes and methylenetriphenylphosphorane
作者:David M. Hodgson、Rosanne S. D. Persaud
DOI:10.1039/c2ob26346g
日期:——
β-Lithiooxyphosphonium ylides, made in situ from an aldehyde and methylenetriphenylphosphorane, react with a second aldehyde to form E-allylic alcohols. α-Branching and α,β-unsaturation in the second aldehyde, together with the lack of further substitution on the phosphorane carbon play important roles in selectivity. A range of these aldehydes, in addition to aromatic aldehydes as the second aldehyde also provided synthetically useful access to E-allylic alcohols.
Formal hydrochromation of an alkyne leading to a 1-substituted ethenylchromium reagent is accomplished by addition of the alkyne and water to a mixture of low-valent chromium(II), a catalytic amount of nickel(II), and triphenylphosphine in DMF.
Regioselective Reductive Coupling of Alkynes and Aldehydes Leading to Allylic Alcohols
作者:Kazuhiko Takai、Shuji Sakamoto、Takahiko Isshiki
DOI:10.1021/ol0272996
日期:2003.3.1
Treatment of a mixture of a terminal alkyne and an aldehyde with CrCl(2) and a catalytic amount of NiCl(2) and triphenylphosphine in the presence of water in DMF at 25 degrees C gives a 1,2-disubstituted allylicalcohol regioselectively.
Alkenes from β-lithiooxyphosphonium ylides generated by trapping α-lithiated terminal epoxides with triphenylphosphine
作者:David M Hodgson、Rosanne S D Persaud
DOI:10.3762/bjoc.8.219
日期:——
Terminal epoxides undergo lithium 2,2,6,6-tetramethylpiperidide-induced alpha-lithiation and subsequent interception with Ph(3)P to provide a new and direct entry to beta-lithiooxyphosphonium ylides. The intermediacy of such an ylide is demonstrated by representative alkene-forming reactions with chloromethyl pivalate, benzaldehyde and CD(3)OD, giving a Z-allylic pivalate, a conjugated E-allylic alcohol