A chiral ligand mediated aza-conjugate addition strategy for the enantioselective synthesis of β-amino esters that contain hydrogenolytically sensitive functionality
摘要:
Aza-conjugate addition of the lithium anion of N-trimethylsilyl-p-methoxybenzylamine to tert-butyl enoate acceptors, in the presence of a stoichiometric amount of enantiopure 1,2-dimethoxy-1,2-diphenylethane and excess trimethylsilyl chloride, affords tert-butyl-N-p-methoxybenzyl-beta-amino esters with excellent levels of enantiocontrol. These N-p-methoxybenzyl-beta-amino-esters may be deprotected under oxidative conditions via treatment with ceric ammonium nitrate, followed by acid hydrolysis of the resultant imine intermediates, to afford enantiopure beta-amino-esters containing hydrogenolytically sensitive functionality. (C) 2015 Elsevier Ltd. All rights reserved.
Alkylthionitroso and arylthionitroso compounds generated from N-trimethylsilyl-N-chlorothioalkylamine precursors
作者:Martin R. Bryce、Antony Chesney、Julie N. Heaton、Graham N. McKelvey、Martin Anderson
DOI:10.1016/s0040-4039(00)77083-3
日期:1994.7
A range of alkylthionitroso and arylthionitroso compounds have been generated by thermal fragmentation of N-trimethylsilyl-N-chlorothioalkyl(aryl)amine precursors, and intercepted by reaction with dimethylbutadiene to afford Diels-Alder and ene adducts.
Zirconium Hydroaminoalkylation. An Alternative Disconnection for the Catalytic Synthesis of α-Arylated Primary Amines
作者:Ana Koperniku、Paul J. Foth、Glenn M. Sammis、Laurel L. Schafer
DOI:10.1021/jacs.9b10465
日期:2019.12.4
Primaryamine products have been prepared using zirconium catalyzed hydroaminoalkylation of alkenes with N-silylated benzylamine substrates. Catalysis using commercially available Zr(NMe2)4, affords an alternative disconnection to access α-arylated primaryamines upon aqueous work-up. Substrate dependent regio- and diastereoselectivity of the reaction is observed. Bulky substituents on the terminal
Organosilicon synthesis of isocyanates: II. Synthesis of aliphatic, carbocyclic, and fatty-aromatic isocyanates
作者:A. V. Lebedev、A. B. Lebedeva、V. D. Sheludyakov、S. N. Ovcharuk、E. A. Kovaleva、O. L. Ustinova
DOI:10.1134/s1070363206030182
日期:2006.3
Silylation of a series of aliphatic, carbocyclic, and fatty-aromatic amines gave the corresponding silyl derivatives whose yield depended on the electronic and steric structure of the substrate and the nature of the silylating agent. The yield of isocyanates obtained by phosgenation of the silyl derivatives under mild conditions decreased in going from aliphatic amines to benzylamines and rose as the length of the alkyl chain in fatty-aromatic amines extended. The most convenient procedure for the synthesis of low-boiling alkyl isocyanates was found to be based on the transformation of amines or ammonium salts into silyl or silyl silyl-carabamates. followed by pyrolysis of the latter in the presence of trichloro(phenyl)silane.
Reactions of Secondary Amines with Bis(η<sup>5</sup>:η<sup>1</sup>-pentafulvene)titanium Complexes: Formation of Titanium Amides and Titanaaziridines
The reactions of bis (eta(5):eta(1)-pentafulvene)titanium complexes (1) with 19 different secondary amines (Aa-s) have been investigated. Depending on the substitution pattern of 1 and nature of the amine used, different reaction products are formed. With use of bis(eta(5):eta(1)-di(p-tolyl)-pentafulvene)titanium (1b) and N-methylanilines (Aa,b), N-methylbenzylamines (Ac,d), N-methylcyclohexylamine (Ae), and dibenzylamine (Af), titanium monoamides of the type (eta(S)-C5H4CH(p-tolyl)(2))(eta(5):eta(1)-C5H4=C(p-tolyl)(2)TiNR2 (2a-f) have been isolated in high yields and characterized, including by single-crystal X-ray diffraction. By the reactions of eta(5):eta(1)-adamantylidene)titanium (1a) and Af, diethylamine (Ag), and 2-methylpiperidine (Ah) similar monoamides 3f-h are formed. The formation of titanium bis-amides employing different types of secondary amines (Aa-s) is not observed. The formation of titanaaziridines is observed exclusively by using 1a and N-methylanilines (Aa,b), N-benzylphenylamine (Ai), and N-benzyltrimethylsilylamines (Aj,k). The titanaaziridine 4i undergoes a regioselective ring enlargement reaction with 1-hexyne. By the reaction of 4i and phenylacetylene a ring opening with formation of (Cp-Ad)(2)Ti(NPh(CH2Ph)CCPh) (6) is observed. The acetylide 6 undergoes a thermal decomposition to give the zigzag butadiyne complex 7. In addition to the ring enlargement of 4j by, ketones a ketone insertion in the titanium-Cp bond is found, as proved for 8 by single-crystal X-ray diffraction.
Bryce Martin R., Chesney Antony, Heaton Julie N., McKelvey Graham N., And+, Tetrahedron Lett, 35 (1994) N 29, S 5275- 5278
作者:Bryce Martin R., Chesney Antony, Heaton Julie N., McKelvey Graham N., And+