Syntheses of 2‐Unsubstituted 1H‐1, 3‐Benzazaphospholes from N‐Formyl‐2‐bromoanilides. Issue 6 (5th September 2013)

• Record Type: Journal Article
• Authors: Ghalib, Mohammed; Niaz, Basit; Jones, Peter G.; Heinicke, Joachim W.
• Is Part Of: Heteroatom chemistry. Volume 24:Issue 6(2013:Nov.)
• Page Start: 452
• Page End: 459
• Publication Date: 2013-09-05
• Subjects: Heterocyclic chemistry -- Periodicals; 547.59
• DOI: 10.1002/hc.21111
• Languages: English
• ISSNs: 1042-7163

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p>The phosphonylation of 2‐bromo‐formylanilides <bold>1</bold> with triethyl phosphite in the presence of preformed Pd(0)(triethyl phosphite)_n catalyst furnished 2‐phosphono‐formanilides <bold>2</bold> in good yields. Reduction with excess LiAlH₄ provided mainly N‐methyl‐2‐phosphinoanilines <bold>3</bold> and minor amounts of 1, 2‐unsubstituted benzazaphospholes <bold>4</bold>. N‐Methyl‐1, 3‐benzazaphospholes <bold>5</bold> were synthesized by the cyclocondensation of <bold>3</bold> with dimethylformamide dimethylacetal (DMFA). A more convenient route to <bold>5</bold>, avoiding the chromatographic separation of <bold>4</bold>, is the reduction of <bold>1</bold> to 2‐bromo‐N‐methylaniline <bold>6</bold>, followed by phosphonylation to <bold>7</bold>, LiAlH₄ reduction, and cyclization with DMFA. The coordination properties at σ²P of benzazaphospholes are characterized by structural data obtained by the crystal structure analysis of (<bold>5b</bold>)W(CO)₅.</p> </abstract>