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

Abstract

SummaryAn 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 1H, 13C, and 31P spectroscopy.

Approach to the Synthesis of Five-Membered Organophosphorus Compounds via Alumoles and Alumolanes

“…In 2012, 3-substituted phospholanes were obtained [13,14]. It was found that aluminocyclopentanes 1 obtained by the reaction of alkenes with Et 3 Al in the presence of 5 mol.…”

“…In the reaction of styrene or 2-vinylnaphthalene with AlEt 3 in the presence of Cp 2 ZrCl 2 , in addition to 3-phenyl(naphthyl)-1-ethylaluminumcyclopentanes 5, the reaction mixture contains 2-phenyl(naphthyl)-1-ethylaluminumcyclopentane 6 [14]. Both regioisomers react in situ with phosphorus dihalides and hydrogen peroxide to form 1-phenyl(alkyl)-3arylphospholane oxides 7 and 1-phenyl(alkyl)-2-arylphospholane oxides 8 in a 1:2 ratio with a total yield of 87% (Scheme 3).…”

“…It was established that, under the developed conditions, bisaluminacyclopentanes 9, obtained by the catalytic cycloalumination of 1,5-hexadiene, 1,7-octadiene, and Next, we thought it expedient to apply our method to obtain α,ω-bisphospholane compounds by the interaction of phosphorus dihalides with bisaluminacyclopentanes. It was established that, under the developed conditions, bisaluminacyclopentanes 9, obtained by the catalytic cycloalumination of 1,5-hexadiene, 1,7-octadiene, and 1,9-decadiene, react with phosphorus dihalides to form bisphospholanes 10 as a mixture of isomers with a total yield of 84-85% (Scheme 4) [14]. Next, we thought it expedient to apply our method to obtain α,ω-bisphospholane compounds by the interaction of phosphorus dihalides with bisaluminacyclopentanes.…”

The mechanism of the replacement of aluminum atoms in 1-ethyl-3-alkylalumolanes by boron atoms with boron halides

“…Alumolanes are rare five-membered aluminacarbocycles, of which the 1-ethyl-3-substituted alumolanes are well-known representatives and are of particular interest as intermediate synthons. Various important sulphur-containing cyclic compounds, 1–3 alcohols, 4–6 hard-to-obtain spirocarbocycles, 1,7 borolanes, 8,9 phospholanes 10,11 and selenium-containing heterocycles 1–3 were synthesized (Scheme 1). Initial cyclic organoaluminum compounds (OACs) are formed under mild conditions (r.t.) by the cycloalumination reaction of α-olefin with AlEt 3 catalyzed by Cp 2 ZrCl 2 .…”

Mechanism of Cp2ZrCl2-Catalyzed Olefin Cycloalumination with AlEt3: Quantum Chemical Approach

“…The less studied is the reaction of Cp 2 ZrCl 2 -catalyzed cycloalumination of α-olefins with AlEt 3 (Scheme ), which provides 1-ethyl-3-substituted alumolanes, the structure of which was proved by multinuclear NMR spectroscopy, applied as the in situ synthons for the preparation of a broad range of functionally substituted derivatives . To date, the latest data indicate the possibility of the one-pot transformations of alumolanes into various classes of organic molecules, for example, phospholanes and borolanes . Moreover, catalytic cycloalumination of unsaturated compounds can serve as an efficient method for the functionalization of steroids and monoterpenes .…”