Reaction of 2H‑Azirine-Phosphine Oxides and -Phosphonates with Enolates Derived from β‑Keto Esters

• Published in: Journal of organic chemistry 2016-01, Vol.81 (1), p.100-108
• Main Authors: Vélez del Burgo, Ander, Ochoa de Retana, Ana M, de los Santos, Jesús M, Palacios, Francisco
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.5b02347

Cyclopenta­[b]-pyrrole-2-phosphine oxides 4a and -phosphonates 4b,c are generated by the addition of cyclic enolates derived from ethyl 2-oxo-cyclopentanecarboxylate 2 to phosphorated 2H-azirines 1. However, the addition of enolate derived from acyclic 2-oxo-butanoate 10 to 2H-azirine phosphine oxide 1 led to vinylogous N-acyl-α-aminoalkyl phosphine oxides 12, involving the carbonyl group and the Cα of the keto ester 10. Ring closure of vinylogous derivative 12 in the presence of base afforded pyrrole-2-phosphine oxide 11. The addition of enolates derived from indenone-carboxylate 15 to 2H-azirines 1 led to the formation of functionalized N-substituted 1H-benzo­[d]­azepine derivatives 17.