SYNTHESIS,REACTIVITY AND CONFORMATION OF 10,11-DIHYDRODIBENZO-[b,f]PHOSPHEPIN AND DIBENZO[b,f]PHOSPHEPIN DERIVATIVES. PHOSPHORUS ANALOGUES OF IMINOBIBENZYL ANTIDEPRESSANTS

Abstract

Derivatives of the novel dibenzob,f]phosphepin system are prepared from 10,11-dihydro-5-phenyl-5H-bibenzob,f]phosphepin 5-oxide (2). New members in the 10,11-dihydro-5H-dibenzob,f]phosphepin series, including phosphorus analogues (7, 10) of the andidepressant drug imipramine (30), are also reported. Products of nucleophilic substitution at tetrahedral phosphorus in 2 appear to be determined by the relative apicophilicity of the nucleophile. Conformational analysis based on ¹H NMR data suggests folded (“butterfly”) conformation for the tricyclic compounds. The twisted boat conformation of the central ring in the 10,11-dihydro compounds bears a pseudo-equatorial Pdbnd]O oxygen or a Pdbnd]S sulfur, in solution. Symmetric AA‘BB’ spin systems are found in 4,5 and 7, and their solution conformations appear to be similar to those of analogous 10,11-dihydrodibenzob,f]azepine derivatives. The interaction of some compounds with NMR shift reagents and their mass spectral fragmentations are discussed.