Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

Abstract

An efficient one-pot process for the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes was developed. The method involves the replacement of aluminium in aluminacyclopentanes, prepared in situ by catalytic cycloalumination of α-olefins and α,ω-diolefins, by phosphorus atoms on treatment with dichlorophosphines (R'PCl2). Hydrogen peroxide oxidation and treatment with S8 of the synthesized phospholanes and α,ω-bisphospholanes afforded the corresponding 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-oxides, 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-sulfides, bisphospholane 1,1'-dioxides, and bisphospholane 1,1'-disulfides in nearly quantitative yields. The complexes LMo(CO)5 (L = 3-hexyl-1-phenylphospholane, 3-benzyl-1-methylphospholane, 1,2-bis(1-phenylphospholan-3-yl)ethane, and 1,6-bis(1-phenylphospholan-3-yl)hexane were prepared by the reaction of 3-substituted phospholanes and α,ω-bisphospholanes with molybdenum hexacarbonyl. The structure of the complexes was proved by multinuclear (1)H, (13)C, and (31)P spectroscopy.

Keywords: Dzhemilev reaction; aluminacyclopentanes; molybdenum complexes; phospholanes; zirconium complexes.

Scheme 1

Synthesis of 3-substituted phospholanes according to earlier data [–17].

Scheme 2

Synthesis of 3-substituted phospholanes.

Scheme 3

Synthesis of 3-substituted phospholane oxides and sulfides.

Scheme 4

Synthesis of 3-substituted 7a–f and 2-substituted 8a–f phospholanes.

Scheme 5

Synthesis of bisphospholanes.

Scheme 6

Synthesis of bisphospholane-1,1'-oxides and bisphospholane-1,1'-sulfides.

Scheme 7

Synthesis of the molybdenum complex (3-hexyl(benzyl)-1-phenyl(methyl)phospholane)Mo(CO)₅.

Scheme 8

Synthesis of molybdenum complexes (1,2(1,6)-bis(1-phenylphospholan-3-yl)ethane(hexane))Mo(CO)₅.