A STUDY OF 1-METHYLPHOSPHOLE AS A HETEROAROMATIC SUBSTANCE

A new phosphole synthesis was devised to provide 1-methylphosphole. 1-Methyl-3-phospholene 1-oxide was converted to the 3,4-dibromide, which was then reduced to the phosphine with trichlorosilane. Dehydrohalogenation with potassium t-butoxide provided the phosphole. Physical evidence suggested considerable cyclic derealization of the ring π systems, e.g., the nmr spectra revealed strong deshielding of ring and P-CH3 protons as well as of 31P, and the ultraviolet spectrum showed strong resemblance to that of N-methylpyrrole. Chemically, the phosphole was exceptionally weak as a base and was not prone to undergo certain phosphine complexation reactions; it did, however, react with oxidizing agents and quaternizing halides. The system seems best described as possessing considerable delocalization but retaining the highly characteristic reducing and nucleophilic properties of phosphines. © 1969, American Chemical Society. All rights reserved.