One-Pot Catalytic Enantio- and Diastereoselective Syntheses of <i>anti</i>-, <i>syn</i>-<i>cis</i>-Disubstituted, and <i>syn</i>-Vinyl Cyclopropyl Alcohols
作者:Hun Young Kim、Luca Salvi、Patrick J. Carroll、Patrick J. Walsh
DOI:10.1021/ja907781t
日期:2010.1.13
Enantioselective addition to aldehydes generates the requisite dienyl zincalkoxides, which are then subjected to in situ cyclopropanation to furnish vinyl cyclopropyl alcohols. Cyclopropanation occurs at the double bond allylic to the alkoxide. Using this method, syn-vinylcyclopropyl alcohols are obtained in 65-85% yield, 76-93% ee, and > 19:1 dr. To prepare anti-cyclopropanols, enantioselective addition of
Catalytic Asymmetric Generation of (<i>Z</i>)-Disubstituted Allylic Alcohols
作者:Luca Salvi、Sang-Jin Jeon、Ethan L. Fisher、Patrick J. Carroll、Patrick J. Walsh
DOI:10.1021/ja0762285
日期:2007.12.1
one-pot method for the direct preparation of enantioenriched (Z)-disubstituted allylicalcohols is introduced. Hydroboration of 1-halo-1-alkynes with dicyclohexylborane, reaction with t-BuLi, and transmetalation with dialkylzinc reagents generate (Z)-disubstituted vinylzinc intermediates. In situ reaction of these reagents with aldehydes in the presence of a catalyst derived from (-)-MIB generates (Z)-disubstituted
Selective lithiation of 1,6-dihalohex-1-enes and 1,6-dihalohex-1-ynes
作者:Abdeslam Abou、Francisco Foubelo、Miguel Yus
DOI:10.1016/j.tet.2007.03.106
日期:2007.7
The lithiation of 1-choro- and 1-bromo-6-chlorohex-1-yne (2, 3) with lithium naphthalene in the presence of benzaldehyde in THF at −78 °C leads after hydrolysis with water to the corresponding chloroalkynol (5) resulting from a regioselective lithiation at the alkynylic position. However, the lithiation of 1-chloro-6-iodohex-1-yne (4) under the same reaction conditions and using pentan-3-one as electrophile
First Catalyzed Hydration of Haloalkynes by a Recyclable Catalytic System
作者:Huaxu Zou、Weibao He、Qizhi Dong、Ruijia Wang、Niannian Yi、Jun Jiang、Dongming Pen、Weimin He
DOI:10.1002/ejoc.201501198
日期:2016.1
The hydration of haloalkynes to give α-halomethyl ketones was achieved based on a combination of a Cu(OAc)2 catalyst and a TFA (trifluoroacetic acid) promoter. This is the first synthesis of chloro/bromo/iodo methyl ketones through a hydration reaction catalyzed by a recyclable catalytic system. The catalytic system has a wide substrate scope and excellent chemoselectivity, and the procedure can also
Gold-Catalyzed Hydration of Haloalkynes to α-Halomethyl Ketones
作者:Longyong Xie、Yundong Wu、Weiguo Yi、Lei Zhu、Jiannan Xiang、Weimin He
DOI:10.1021/jo401437w
日期:2013.9.20
A general atom-economical approach for the synthesis of alpha-halomethyl ketones is demonstrated through hydration of a wide range of haloalkynes. Other outstanding features include excellent yields from both alkyl- and aryl-substituted haloalkynes and wide functional group tolerance. This protocol is an alternative to conventional alpha-halogenation of ketones.