Aza- wittig reaction of N-vinylic phosphazenes with carbonyl compounds. Azadiene-mediated synthesis of isoquinolines and 5,6-dihydro-2H-1,3-oxazines

摘要

N-Vinylic phosphazenes 4 are obtained by reaction of hosphorus ylide 5 and nitriles 6. Aza- Wittig reaction of phosphazenes 4 with aldehydes leads to the formation of 2-azadienes 1, which Are easily converted into isoquinolines 2. Reaction of conjugated phosphazenes 4 with ethyl Glyoxalate affords 5,6-dihydro-2H-1,3-oxzzines 9 in a region- and stereoselective fashion, while Heterodienes 1 react with ethyl glyoxalate and diethyl ketomalonate giving 1,3-oxazines 11 and 12.