Lipase-mediated kinetic resolution of allylic(hydroxymethyl)methylenecyclopentane building blocks
摘要:
Enzymatic-mediated kinetic acylation of allylic(hydroxymethyl)methylenecyclopentane building blocks (+/-)-1a,b is reported using various commercially available lipases, Lipase Amano AK (Pseudomonas sp.) proved to be the best lipase in the case of (-)-1b which was obtained with a 96% enantiomeric excess. Single crystal X-ray diffraction analysis, using the (1S,4R)-camphanate derivative of (-)-1b, helped us to assign the S absolute configuration of (-)-1b and the enantiomeric specificity of the tested lipases. (C) 2000 Elsevier Science Ltd. All rights reserved.
Selective Generation of Free Radicals from Epoxides Using a Transition-Metal Radical. A Powerful New Tool for Organic Synthesis
作者:T. V. RajanBabu、William A. Nugent
DOI:10.1021/ja00082a021
日期:1994.2
halogens provides a route to functionalized cyclopentanes and other useful products. The radical initially formed from an epoxide can also be trapped by H-atom donors such as 1,4- cyclohexadiene or tert-butyl thiol, resulting in an overall reduction of the epoxide. In the absence of a H-atom donor or an olefin, this radical is trapped by Ti(", resulting in a fl-oxido-Ti organometallic species which undergoes
Stabilization of reactive aldehydes by complexation with methylaluminum bis(2,6-diphenylphenoxide) and their synthetic application
作者:Keiji Maruoka、Arnel B. Concepcion、Noriaki Murase、Masataka Oishi、Naoki Hirayama、Hisashi Yamamoto
DOI:10.1021/ja00063a013
日期:1993.5
Reactive aldehydes such as formaldehyde and α-chloro aldehydes can be successfully generated by treatment of readily available trioxane and α-chloro aldehyde trimers, respectively, with methylaluminum bis(2,6-diphenylphenoxide) (MAPH), and stabilized as their 1:1 coordination complexes with MAPH. The resulting CH 2 =O.MAPH complex reacts with a variety of olefins to furnish ene-reaction products with