Rearrangement of 3-alkylidene-2-siloxy-tetrahydro-1,2-oxazines (ASENA). A new approach toward the synthesis of 3-α-hydroxyalkyl-5,6-dihydro-4H-1,2-oxazines
作者:Andrey A. Tabolin、Alexey V. Lesiv、Yulia A. Khomutova、Yulia V. Nelyubina、Sema L. Ioffe
DOI:10.1016/j.tet.2009.03.082
日期:2009.6
A new approach toward the synthesis of 3-alpha-hydroxyalkyl-5,6-dihydro-4H-1,2-oxazines 1 from available 5,6-dihydro-4H-1,2-oxazine N-oxides 2 has been described. The key step of the process-the rearrangement of 3-alkiliden-2-siloxy-tetrahydro-1,2-oxazines 3 (ASENA)-was thoroughly investigated. Optimal experimental conditions were developed. A possible pathway of the ASENA rearrangement was proposed. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis of α-Prolinols and 2-Amino-1,5-diols from Primary Nitroalkanes and Other Simple Precursors via Intermediacy of 5,6-Dihydro-4H-1,2-oxazines
A new strategy for the synthesis of 2-(1-hydroxyalkyl)pyrrolidines and 2-amino-1,5-diols is suggested. The target compounds can be obtained in high yields from available precursors through the intermediacy of six-membered cyclic nitronates and their rearrangement products. Successive reduction of the latter led to the target products with moderate to high diastereoselectivity.
2-Silyloxy-1,2-oxazines, a New Type of Acetals of Conjugated Nitroso Alkenes
作者:Alexander A. Tishkov、Alexey V. Lesiv、Yulya A. Khomutova、Yury A. Strelenko、Ivan D. Nesterov、Michael Yu. Antipin、Sema L. Ioffe、Scott E. Denmark
DOI:10.1021/jo034669a
日期:2003.11.1
3-alkyl-substituted 1,2-oxazine N-oxides 2 can be selectively transformed into 2-silyloxy-1,2-oxazines 1 upon treatment with silylating reagents. In the solidstate derivatives 1 adopt a chair conformation with the pyramidal nitrogen atom, whereas in solution they exist as an equilibrating mixture of two conformers (DeltaG++ 55-60 kJ/mol). A preliminary study of the reactivity of nitrosals 1 has shown