Enantioselective addition of diethylzinc to aldehydes catalyzed by monosubstituted [2.2]paracyclophane-based N,O-ligands: remarkable cooperative effects of planar and central chiralities
摘要:
Diastereomeric monosubstituted [2.2]paracyclophane-based N,O-ligands, which unite the planar and central chiral elements, were optimized for the enantio selective diethylzinc addition to aldehydes. (S)-1-{(S-p)-[2.2]Paracyclophan-4-yl} methyl-2-pyrrolidine-alpha,alpha-diphenylmethanol (S-p,S)-3 catalyzed the addition to give (R)-1-phenyl-l-propanol in a high yield and with a good enantio selectivity (91% ee). (c) 2006 Elsevier Ltd. All rights reserved.
α-Aminated methyllithium by DTBB-catalysed lithiation of a N-(chloromethyl) carbamate
作者:Javier Ortiz、Albert Guijarro、Miguel Yus
DOI:10.1016/s0040-4020(99)00155-6
日期:1999.4
The reaction of O-tert-butyl-N-(chloromethyl)-N-methylcarbamate (1) with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 2.5 mol %) in the presence of different electrophiles [Me3SiCl, iBuCHO, tBuCHO, PhCHO, 4-MeOC6H4CHO, (CH2)4CO, MeCOnPr, Et2CO, MeCO(CH2)2CHCH2, PhCOMe, PhCOnBu, Ph2CO] in THF at −78°C leads, after hydrolysis with water, to the expected functionalised
O-tert-Butyl-N-(chloromethyl)-N-methyl carbamate as a source of the MeNHCH2− synthon
作者:Albert Guijarro、Javier Ortiz、Miguel Yus
DOI:10.1016/0040-4039(96)01134-3
日期:1996.7
The reaction of O-tert-butyl-N-(chloromethyl)-N-methylcarbamate (1) with lithium powder and a catalytic amount of DTBB (2.5 mol %) in the presence of different electrophiles [Me3SiCl, BuiCHO, ButCHO, PhCHO, (CH2)4CO, Et2CO, PhCOMe, Ph2CO] in THF at −78°C leads, after hydrolysis with water, to the expected functionalised carbamates 2. As an example, the hydrolysis of compound 2e with hydrogen chloride
A compound of formula (I), or stereoisomers or pharmaceutically acceptable salts thereof,
wherein, R
1a
, R
1b
, R
2a
, R
2b
, U
1
, U
2
, X
1
, X
2
and L are as defined herein.