Asymmetric synthesis and applications of β-amino Weinreb amides: asymmetric synthesis of (S)-coniine
作者:Anthony J. Burke、Stephen G. Davies、A. Christopher Garner、Tom D. McCarthy、Paul M. Roberts、Andrew D. Smith、Humberto Rodriguez-Solla、Richard J. Vickers
DOI:10.1039/b402531h
日期:——
Conjugate addition of lithium (S)-N-benzyl-N-alpha-methylbenzylamide to a range of alpha, beta-unsaturated Weinreb amides proceeds with high levels of diastereoselectivity (>95% de). The beta-amino Weinreb amide products may be transformed into beta-amino ketones via reactions with Grignard reagents, while treatment with DIBAL-H furnishes beta-amino aldehydes. Trapping of the aldehyde via Wadsworth-Emmons
Interrupted Pyridine Hydrogenation: Asymmetric Synthesis of δ‐Lactams
作者:Tobias Wagener、Lukas Lückemeier、Constantin G. Daniliuc、Frank Glorius
DOI:10.1002/anie.202016771
日期:2021.3.15
for increasing chemical complexity in a single reaction step. Overcoming the tenet of full reduction in arene hydrogenation has been seldom demonstrated. In this work we report the synthesis of sought‐after, enantioenriched δ‐lactams from oxazolidinone‐substituted pyridines and water by an interrupted hydrogenation mechanism.
(1) have been assembled in a highlydiastereoselective manner by addition of allyllithium to chiral SAMP hydrazones followed by N-acylation with acryloyl chloride. Substrates 1 undergo ring-closing metathesis to give the cyclic enehydrazides (5) which can be easily converted into virtually enantiopure 6-alkyl- or 6-arylpiperidin-2-ones (7). The versatility of this hydrazone addition-RCM protocol has been
Asymmetric Synthesis of Unsaturated Monocyclic and Bicyclic Nitrogen Heterocycles
作者:Hiroshi Nomura、Christopher J. Richards
DOI:10.1021/ol900880w
日期:2009.7.2
Hydrolysis of scalemic trichloroacetamides Cl3CCONHCH(R)CHCH2 and allylation, or acylation with but-3-enoic acid, followed by ring-closing metathesis resulted in the formation of unsaturated pyrrolidine and piperidine building blocks. These were employed in the synthesis of (S)-coniine (R = Pr) and a formal synthesis of (+)-anisomycin (R = p-MeOC5H4). Extension of this methodology with R = CH2CHCH2 employing two ring-closing metatheses resulted in the synthesis of unsaturated quinolizidinone and indolizidinone frameworks.
New highly enantioselective synthesis of 6-alkylpiperidin-2-ones and 2-substituted piperidines
作者:Stéphanie Fréville、Jean Pierre Célérier、Vu Moc Thuy、Gérard Lhommet
DOI:10.1016/0957-4166(95)00348-s
日期:1995.11
A versatile and highly enantioselective approach to 2-substituted piperidines is described using phenylglycinol as chiral auxiliary.