A new method for the generation of α-nitrosoolefins from ketooximes and its application to the synthesis of 5,6-dihydro-4<i>H</i>-1,2-oxazine derivatives
作者:S. L. Gaonkar、K. M. Lokanatha Rai
DOI:10.1002/jhet.5570420520
日期:2005.7
treatment with tri-ethylamine leads to the formation of α-nitrosoolefins via α-nitrosochloride, which can react in situ intermol-ecularly with olefinic compounds to produce 5,6-dihydro-4H-1,2-oxazine derivatives in good yield.
含α-亚甲基的酮肟与氯胺-T反应,然后用三乙胺处理,可通过α-亚硝基氯化物形成α-亚硝基烯烃,后者可与烯烃化合物在分子间原位反应生成5,6-二氢-4 H -1,2-恶嗪衍生物的收率高。
Cycloaddition of dienes to nitroso- and azo-alkenes
作者:Roy Faragher、Thomas L. Gilchrist
DOI:10.1039/c39760000581
日期:——
Furan, 2,5-dimethylfuran, and cyclopentadiene add to the nitroso- and azo-alkenes (1) and (2) to give the oxazine and pyridazine derivatives (3) and (4); a mechanism involving Diels-Alder addition followed by rapid [3,3] rearrangement is proposed.
Treatment of the two known (oxazine)1,4-adducts of α-nitrosostyrene and either 2,5-dimethylfuran or cyclopentadiena with further nitrosostyrene give nitrones, products of 1,3-addition at the oximion CN.
A novel [4 + 1] dearomative spiroannulation of α-halo-β-naphthol and nitroolefin has been developed for the direct construction of various spiroisoxazolidines in high chemo- and diastereoselectivity. Notably, halophenols (X = Cl and I) were also tolerated by this reaction. This transformation was realized through a sequence of electrophilic dearomatization/dehalogenation, and mechanistic studies revealed