[reaction: see text] alpha-Acetoxynitroso compound 3 has been prepared as a new stable, isolable, and reactive dienophile in nitroso Diels-Alder reactions. The yield of the [4 + 2] cycloaddition of alpha-acetoxynitroso dienophile with 1,3-dienes could be enhanced in the presence of 20 mol % Lewis acid. An unexpected retro hetero-Michael reaction from 26 was observed, leading to the cleavage of the
Process for the preparation of 5-amino-1,3-dioxanes
申请人:Zambon Group S.p.A.
公开号:US05663372A1
公开(公告)日:1997-09-02
Described herein is a process for the preparation of 5-amino-1,3-dioxanes of formula (I), wherein R and R.sub.1 have the meanings reported in the description, comprising the catalytic hydrogenation of the new oximes of formula (II).
α-Acyloxynitroso dienophiles in [4+2] hetero Diels–Alder cycloadditions: mechanistic insights
作者:Géraldine Calvet、Susannah C. Coote、Nicolas Blanchard、Cyrille Kouklovsky
DOI:10.1016/j.tet.2010.02.065
日期:2010.4
alpha-Acyloxynitroso derivatives are a class of heterodienophiles leading to valuable 3,6-dihydro-1,2-oxazines or the corresponding aminoalcohols in good yields. The discovery that a beta-oxygenated moiety led to a domino [4+2] cycloaddition/sigma(N-O) bond cleavage in the presence of a catalytic amount of Lewis acid was investigated in detail, through kinetic profiling of the reaction both in the absence and presence of a promoter. These studies showed that the role of the Lewis acid was to accelerate the sigma(N-O) bond cleavage thereby promoting a highly reproducible sequence. In addition, our preliminary results on an asymmetric version of this domino sequence are reported. (C) 2010 Elsevier Ltd. All rights reserved.
Majewski, Marek; Gleave, D. Mark; Nowak, Pawel, Canadian Journal of Chemistry, 1995, vol. 73, # 10, p. 1616 - 1626
作者:Majewski, Marek、Gleave, D. Mark、Nowak, Pawel
DOI:——
日期:——
2,2-Dimethyl-5-nitroso-1,3-dioxan-5-yl benzoate, 2,2-dimethyl-5-nitroso-1,3-dioxan-5-yl 4-chlorobenzoate and 5-nitroso-1,3-dioxan-5-yl 4-chlorobenzoate
The crystal structures of 2,2- dimethyl-5-nitroso-1,3-dioxan-5-yl benzoate, C13H15NO5, (1), 2,2-dimethyl-5-nitroso-1,3-dioxan-5-yl 4-chlorobenzoate, C13H14ClNO5, (II), and 5-nitroso-1,3-dioxan-5-yl 4-chlorobenzoate, C11H11NO5, (III), have been determined in order to gain insight into the conformational preference of alpha-benzoyloxynitroso. Unfavourable 1,3-diaxial interactions force (I) and (II) to crystallize in the 2,5 twist-boat conformation, whereas compound (III), lacking this destabilizing interaction, crystallizes in the chair conformation.