Serendipitous Discovery of a Phosphirene−Phosphindole Rearrangement

Abstract

The reaction of strong Lewis acids with 2-amino-3phenylphosphirene pentacarbonyltungsten complexes leads to the corresponding 2-aminophosphindoles through the unexpected formation of a bond between phosphorus and one of the ortho carbons of the phenyl ring.

Alkyne Insertion into P–C(sp2) Bonds as a Route to Fused Phospholes: Transition-Metal-Like Reactivity at Phosphorus

“…The P−C distance of 1.839(2) on the alkene side of the phosphole ring is consistent with those reported for W coordinated benzophosphole rings; however, the P−C bond distance on the ring-fused side (1.786(2) Å) is significantly shorter than those in benzophosphole rings. 10,12,17,28 In contrast to the phosphole ring, the pyrrole ring is clearly aromatic. This is evident from the ring planarity (mean deviation of atoms from plane = 0.002 Å), the planarity of the N atom (sum of angles = 359.7°), and the bond lengths within the ring.…”

“…Fused phospholes have applications as components for optoelectronic materials − and also have been used as ligands for catalytic applications. , As a result, synthetic routes to fused phospholes are of great interest. They are most commonly synthesized via metalation-cyclization ,,, or through transition-metal-catalyzed alkyne annulation reactions. − Other methods applied to their synthesis include Fagan–Nugent Ti mediated cyclization, rearrangement of phosphirenes, intramolecular CH activation by phosphinidene complexes, and photocatalyzed annulation reactions . The alkyne annulation reactions, whether metal-mediated or photocatalyzed, offer very efficient routes to benzophospholes; however, regioselectivity remains a challenge, with mixtures of direct and rearranged products resulting.…”

Developing a new phosphorus-carbon bond synthesis

“…Terminal phosphinidene complexes are able to insert into C-Z bonds (Z = P, N, Ni) to form new P-C bonds. [281,356] The most interesting insertion that [RP→W(CO) 5 ] can undergo is the C-H insertions which form new P-C bonds (Scheme 1.120). [357] Mathey recently reported the synthesis of a series of annulated phosphole complexes via intramolecular phosphinidene C-H insertion (Scheme 1.121).…”

“…[271] The transient [RP→ML n ] can be trapped via [1+2] and [1+4] cycloadditions with various trapping reagents to give a wide variety of P-heterocycles (Scheme 1.88). [279][280][281][282][283] The [1+2] cycloaddition of terminal phosphinidene and alkene proceeds via a concerted mechanism as proved by the retention of stereo-configuration of C 2 unit of phosphirane complex. [284][285] Scheme 1.88 Trapping reactions of terminal phosphinidene complexes.…”

“…Intramolecular ring expansion can also be induced (Scheme 1.114). [281] Scheme 1.114 Ring expansion of phosphirene complex via electrophilic substitution.…”