Enantioselective synthesis of protected d-serine from tetrahydrooxazin-4-one via a hetero Diels–Alder reaction
摘要:
Hetero Diels-Alder reaction between 2-aza-3-trimethylsilyloxy-1,3-diene and aldehydes gives rise to tetrahydrooxazin-4-ones, useful intermediates in the synthesis of alpha-amino-beta-hydroxy acids. Herein we report the complete stereoselective synthesis of D-serine Cbz-methyl ester. (C) 2002 Elsevier Science Ltd. All rights reserved.
well as reaction conditions. Abinitiostudies at MP2/6−31G* and QCISD(T)/6−311G** levels on model compounds provide a rationalization of the experimental results obtained. From the experimental as well as theoretical data it is clear that the presence of the silyl enol group in the intermediate azadiene is crucial in its stabilisation and plays a fundamental role in the conrotatory ringclosure and,
An efficientsynthesis of the lactonic derivative of 2,4-di-epi- polyoxamic acid, in high enantiomeric purity, through a hetero Diels-Alder approach, is reported.
Synthesis of perhydroxazin-4-ones. Competitive Mukaiyama versus hetero Diels–Alder reaction in the cycloaddition of 2-aza-3-trimethylsilyloxy-1,3-butadiene and aldehydes
The reactions of 2-aza-3-trimethylsilyloxy-1,3-butadiene with carbonyl dienophiles are described. 2-Aza-1,3-butadienes participate as dienes in the [4+2] cycloaddition with aldehydes to afford perhydroxazin-4-ones in good yields. Experimental results, however, show that a Mukaiyama type two-step reaction must be taken into account. The cycloadducts obtained have proved to be useful intermediates in the synthesis of alpha -amino-beta -hydroxy acids. (C) 2001 Elsevier Science Ltd. All rights reserved.
Lewis acid-catalyzed electrocyclization of 2-aza-1,3-butadienes to NH-β-lactams
Lewis acid-catalyzed cyclization of 2-aza-3-trimethylsilytoxy-buta-1,3-diene is reported.. Stereochemical differences with the uncatalyzed cyclization are discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.
A general approach to the solution phase parallel synthesis of perhydrooxazin-4-ones, which allows the preparation of milligram quantities of each individual member, is reported. An efficient purification; method, using as "Sequestration Enabling Reagent" (SER) aminomethylpolystyrene resin in the presence of trimethylorthoformate is also described. (C) 1998 Elsevier Science Ltd. All rights reserved.