Synthesis of Halogenated α,β‐Unsaturated γ‐Butyrolactone Derivatives by Triphenylphosphine‐Catalyzed Cyclization of α‐Halogeno Ketones with Dialkyl Acetylenedicarboxylates (=Dialkyl But‐2‐ynedioates)

Abstract

A Ph3P‐catalyzed cyclization of α‐halogeno ketones 2 with dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) 3 produced halogenated α,β‐unsaturated γ‐butyrolactone derivatives 4 in good yields (Scheme 1, Table). The presence of electron‐withdrawing groups such as halogen atoms at the α‐position of the ketones was necessary in this reaction. Cyclization of α‐chloro ketones resulted in higher yields than that of the corresponding α‐bromo ketones. Dihalogeno ketones similarly afforded the expected γ‐butyrolactone derivatives in high yields.

An efficient domino one-pot synthesis of novel spirofuran-indenoquinoxalines by vinyltriphenylphosphonium salts

“…On the basis of the well-established chemistry of trivalent phosphorus nucleophiles, [40][41][42][43] it is reasonable to assume that spiro-1,2-oxaphospholes 7 results from the initial addition of triphenyphosphine 4 (1 mmol) to the acetylenic ester 5 (1 mmol) and subsequent attack of the resulting anion to the carbonyl carbon of the aromatic ketone 44 3 (1 mmol), which apparently cyclizes, in CH 2 Cl 2 at room temperature, to deliver the spiro-1,2-oxaphospholes 7. In the event we did not observe the expected MCR product 7; instead, the reaction afforded the corresponding methyl 4-methoxy a catalyst [45][46][47] in the reaction between the dimethyl acetylenedicarboxylate and 11H -indeno[1,2-b] quinoxalin-11-one 3a (Scheme 2).…”