Enantioselective α-Arylation of O-Carbamates via Sparteine-Mediated Lithiation and Negishi Cross-Coupling
摘要:
A general and enantioselective arylation of carbamates derived from primary alcohols was developed by combining Hoppe's sparteine-mediated asymmetric lithiation with Negishi cross-coupling. Coupled with Aggarwal's lithiation-borylation sequence, the current method provides a short and divergent access to a variety of enantioenriched secondary and tertiary benzylic alcohols.
PREPARATION OF FUNCTIONALIZED ALKOXYAMINE INITIATOR AND ITS USE
申请人:——
公开号:US20030236368A1
公开(公告)日:2003-12-25
A one-pot process for the preparation of functional alkoxyamines of the general formula (I),
1
is disclosed. The process entails (1) reacting an oxidizing agent with a sterically hindered secondary amine to produce an aqueous phase and a nitroxyl radical (2) removing the aqueous phase and adding to the nitroxyl radical one or more vinyl monomer(s) conforming to a formula and a system which produces free radicals. Also disclosed is a process of polymerizing monomers using the functional alkoxyamine.
Quantitative Data on the Effects of Alkyl Substituents and Li–O and Li–N Chelation on the Stability of Secondary α-Oxy-Organolithium Compounds
作者:Pablo Monje、Paula Graña、M. Rita Paleo、F. Javier Sardina
DOI:10.1002/chem.200600864
日期:2007.3.5
more sterically hindered organolithiumcompounds. Alkyl groups adversely affect the stability of organolithiumcompounds when attached to the carbon bearing the negative charge, but the extent of this effect is highly dependent on the nature of the rest of the substituents attached to the anionic center. Quantitative data on the stabilization imparted to organolithiumcompounds by Li-O and Li-N chelation
In-situ polymerization of monoethylenically unsaturated monomers with secondary amines
申请人:——
公开号:US20040122270A1
公开(公告)日:2004-06-24
A process for the preparation of any of well-defined homopolymers, random and block copolymers is disclosed. The process that entails forming a mixture of monomers, a hindered secondary amine and an oxidizing agent is characterized in the absence of any additional free-radical initiator.
Process for the synthesis for alkoxy amines and their use in controlled radical polymerization
申请人:——
公开号:US20040002606A1
公开(公告)日:2004-01-01
A one-pot process for the preparation of alkoxyamines conforming to formulae (I) or (II), preferably (I)
1
is disclosed. The process entails (1) reacting of an oxidizing agent (A) with a sterically hindered secondary amine of the general formula (III),
2
in a water-containing medium to form a reaction product and an aqueous phase, (2) removing of the aqueous phase, and (3) (adding to the reaction product a free-radical initiator (B) under conditions that promote the decomposition of the initiator to generate free radicals. Also disclosed is a process for polymerizing monomers, the process using the alkoxyamine prepared by the inventive process.
A process for the preparation of a compound of the formula ##STR1## which comprises deprotonating a carbamate of the formula ##STR2## in an inert solvent with a selective base, in the presence of a chelate-forming diamine to give a compound of the formula ##STR3## and then reacting III in an inert solvent, either with an achiral electrophile of the formula (IV) or (V) or with an optionally prochiral electrophile of the formula (VI) ##STR4## and in the case in which R.sup.1 represents an electrofugic leaving group, optionally again electrophilically substituted with the formation of an acyl anion and renewed deprotonation, and in a last step, solvolytically removing the protecting group --CO--NR.sup.10 R.sup.11.