Enantioselective synthesis of C2-functionalized, N-protected morpholines and orthogonally N,N′-protected piperazines via organocatalysis
摘要:
In this Letter, we describe a novel three-step, one-pot procedure for the enantioselective synthesis of N-benzyl protected morpholines and orthogonally N,N'-protected piperazines with chiral alkyl groups installed at the C2 position of each heterocyclic core via organocatalysis. This methodology allows for the rapid preparation of functionalized morpholines and piperazines that are not readily accessible through any other chemistry in good to excellent % ee (55-98% ee). (C) 2011 Elsevier Ltd. All rights reserved.
Enantioselective Organocatalytic Synthesis of 2-Oxopiperazines from Aldehydes: Identification of the Elusive Epoxy Lactone Intermediate
作者:Nikolaos Kaplaneris、Constantinos Spyropoulos、Maroula G. Kokotou、Christoforos G. Kokotos
DOI:10.1021/acs.orglett.6b02699
日期:2016.11.18
organocatalytic linchpin catalysis approach was envisaged to convert simple aldehydes into enantioenriched 2-oxopiperazines. A four-step reaction sequence (chlorination, oxidation, substitution, and cyclization) was developed and led to different substitution patterns in high yields and selectivities. The reaction mechanism was studied, and the previously elusive epoxy lactone intermediate was identified by
Chemistry of 1,6-dihydro-1,3-oxazines. XXII. Chemistry of 2-chloromethyl-5,6-dihydro-1,3-oxazines. Grignard coupling and metalation studies. Synthesis of .alpha.-chloroaldehydes and arylacetic acids