A New Approach for Construction of Quarternary Chiral Centers: Preparation of a-Branched Serine Derivatives
作者:Hidemitsu Uno、Hidemitsu Uno、Ken-ichi Kasahara、Noboru Ono
DOI:10.3987/com-00-8863
日期:——
In the presence of a Lewis acid, the Michael-type reaction of (3R)-5-tert-butyldimethylsiloxy-3-phenyl-1H-pyrrolo[1,2-c]oxazole (1) with nitro olefins smoothly occurred to give 7a-alkylated pyrrolo[1,2-c]oxazol-5-ones (2) in good yields. The products (2) were successfully transformed to a alpha-branched serine derivatives via reductive denitration followed by lactam-ring cleavage.
Nitrone [2+3]-Cycloadditions in Stereocontrolled Synthesis of a Potent Proteasome Inhibitor: (−)-Omuralide
作者:Jean-Christophe Legeay、Nicole Langlois
DOI:10.1021/jo701968d
日期:2007.12.1
A new stereocontrolled synthetic route to omuralide has been developed from methyl pyroglutamate. This route involves regio- and stereoselective N-methylnitrone 1,3-dipolar cycloadditions to appropriate pyrrolinones, beta-eliminations, and highly selective hydrogenations as the main steps.
Tandem electrophilic and nucleophilic additions to bicyclic tert-butyldimethylsilyloxypyrrole derived from (S)-pyroglutaminol
作者:Nicole Langlois、Prabir K. Choudhury
DOI:10.1016/s0040-4039(99)00284-1
日期:1999.3
The silyloxypyrrole derivative 3, treated with SnCl4 and aqueous NaHCO3, afforded the 5-hydroxylated pyrrolidinone 7. This compound was shown to be a key intermediate for the diastereoselective introduction of other hetero- and C-nucleophiles at the same position. (C) 1999 Elsevier Science Ltd. All rights reserved.