Issue 16, 2018

Phosphine-catalyzed [4 + 2] annulation of γ-benzyl allenoates: facile synthesis of benzothieno[3,2-b]pyran derivatives

Abstract

An efficient tris(4-methoxyphenyl)phosphine-catalyzed domino reaction between γ-benzyl allenoates and ethyl (Z)-2-(3-oxobenzo[b]thiophen-2(3H)-ylidene)acetate has been developed, which produces a series of 2H-benzo[4,5]thieno[3,2-b]pyran derivatives in high yields. The substrate scope includes both electron-withdrawing (e.g., halogen) and electron-donating (e.g., methoxy) groups on both the benzothiophene and allenoate moieties. The reaction can also be performed on the gram scale with good yield (e.g., 77%). In this reaction, γ-substituted allenoate acts as a two-carbon synthon, in a manner rarely reported in the literature to date.

Graphical abstract: Phosphine-catalyzed [4 + 2] annulation of γ-benzyl allenoates: facile synthesis of benzothieno[3,2-b]pyran derivatives

Supplementary files

Article information

Article type
Paper
Submitted
02 Jan 2018
Accepted
27 Mar 2018
First published
27 Mar 2018

Org. Biomol. Chem., 2018,16, 2885-2892

Phosphine-catalyzed [4 + 2] annulation of γ-benzyl allenoates: facile synthesis of benzothieno[3,2-b]pyran derivatives

S. Ma, A. Yu and X. Meng, Org. Biomol. Chem., 2018, 16, 2885 DOI: 10.1039/C8OB00004B

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