A Convenient Procedure for the Preparation of 1-(Diisopropylamino)phospholes − Application to the Synthesis of New 2,2′-Biphosphole Disulfides

Abstract

A convenient one-pot procedure for the preparation of 1-(diisopropylamino)phospholes has been developed. These phospholes have been used in a multistep procedure for synthesizing two new 2,2Ј-biphosphole disulfide compounds. The structures and stereochemistry of these compounds have been studied by X-ray diffraction analysis and by molecular

The Continuing Development of the Chemistry of Phospholes

“…The usual P-substituents are alkyl or aryl groups, but it has now been shown that a (di-isopropyl)amino substituent can be present provided the dehydrohalogenation is performed with metallic amides such as lithium hexamethyldisilazane (LiHMDS) rather than the usual amine bases [24]. In this new case, the requisite chlorophospholenium chloride 41 was obtained by using the aminophosphenium ion 4 0 as the dienophile in the cycloaddition reaction.…”

“…Finally, oxides of 1-dimethyl-and 1-diethylamino phospholes are known to dimerize on formation [86] but it has recently been found [24] that the larger 1-diisopropylamino group provides sufficient steric hindrance as to make phospholes 210 ( 46.90) and 211 ( 42.98) stable at 40° C for 48 hr. or at 110° C in toluene for 4 hr.…”

“…The 2-bromophosphole sulfides 224 and 225 have been converted to the 2-lithio derivatives 226 and 227, and these have been coupled with CuCl 2 [24] [16].…”

“…Compounds 226 and 227 were also the source of two other phosphole sulfides; thus, incidental hydrolysis led to structures 230 ( 65.5) and 231 ( 64.5), respectively [24].…”

“…Thus, after adding bromine to phosphole oxides 210 and 211, oxygen in the resulting phospholene oxides was replaced by sulfur by reaction with P 4 S 10. Phosphole sulfides 236 ( 62.98) and 2 3 7 ( 63.57) were prepared by dehydrohalogenation of dibromophospholene sulfide 234 and 235, Equation (68) [24]. Similar reactions were used to prepare the sulfides with a P-phenyl group [30].…”