Reaction of allyl iminophosphoranes with ketenes and acyl chlorides: one-pot preparation of 4-pentenenitriles
摘要:
One-pot conversion of allyl azides into 4-pentenenitriles 4 is achieved by sequential treatment of allyl azides with triphenylphosphine and the corresponding ketene under mild and neutral conditions. On the other hand, allyl iminophosphoranes and related react with arylacetic acid chlorides to give unexpectedly the phosphonium salts 5 which by treatment with base and then heating lead to 4-pentenenitriles 9.
New Efficient Synthesis of 5-Ethoxyoxazoles and Oxazolo[3,2-c]quinazolines via Aza-Wittig Reaction
作者:Ming-Wu Ding、Nian-Yu Huang、Yi-Bo Nie
DOI:10.1055/s-0028-1087562
日期:2009.3
5-Ethoxyoxazoles or 2-acylamino propanoates were synthesized by aza-Wittig reaction of iminophosphorane with acyl chloride in the presence of triethylamine. Reactions of 5-alkoxyoxazole with triphenyphosphine produced iminophosphoranes. A tandem aza-Wittig reaction of iminophosphorane with isocyanate or carbon disulfide generated oxazolo[3,2-c]quinazolines in satisfactory yields.
Solvent-free rapid coupling of monothiocarboxylic acid with azide affords carboxamide chemoselectively. Triphenyl phosphine included as an additive influences the chemoselectivity, yielding carboxamide and thioamide. Similar variation in the chemoselectivity is observed in the absence and presence of triphenyl phosphine in solution-phase methodology. Rapidity and ecofriendliness of the solvent-free approach to yield the products in just 15 min is noteworthy compared to the solution-phase protocol, which has a long reaction time (1-3 days).