Tungalag Chuluunbaatar

Phosphine-Boranes Based on the 7-Phosphanorbornene Framework: a Regioselective Approach to the Monoboranes of the Dimers of Phospholes

Abstract The reaction of dimers of phosphole oxides ( 3a – e ) with an excess of dimethylsulfide borane follows an unexpected route to give phosphine-boranes 5a – e based on the 7-phosphanorbornene framework in a regioselective manner and in good yields. In small quantities, the diboranes ( 10a – e ), that can be synthesized in acceptable yields by the reaction of the corresponding diphosphines 12a – e with borane, were also formed.

endo and exo Ring fusion in the Diels–Alder reaction of 1-(2,4,6-trialkylphenyl-)3-methylphospholes with maleic acid derivatives

Abstract Diels–Alder reaction of the title phospholes and N -phenylmaleimide afforded, surprisingly, a mixture of endo and exo fused cycloadducts with the P-aryl substituent anti to the double bond giving, after oxidation the corresponding P-oxides. The P-center of the exo ring fused P-oxides was found to be inverted under the conditions of the oxidation. The cycloaddition of triisopropylphenylphosphole with N -methylmaleimide or with maleic acid anhydride gave the corresponding endo fused phosphanorbornenes affording stable products after oxidation. Relative stability of the possible isomers was evaluated experimentally and by quantum chemical calculations.

Site-selective phosphorylation of arylphospholes through reaction with phosphorus tribromide

The reaction of 1-(tri-tert-butylphenyl)phosphole (1) with phosphorus tribromide gave the 3-dibromophosphino intermediate (2) selectively that was useful in the synthesis of phosphonic amides 4, H-phosphinic amide 6 and H-phosphinates 8. A similar transformation of the 1-(triisopropylphenyl)phosphole (9) led to a 2-substitution furnishing phosphonic amides 12 or H-phosphinates 14. The phosphorylated phospholes (4, 6, 8) were tested as ligands of transition metal complexes in hydroformylation.

One-pot transformation of cyclic phosphine oxides to phosphine–boranes by dimethyl sulfide–borane

Different types of cyclic phosphine oxides, such as tetrahydrophosphole oxide 1, phosphabicyclo[3.1.0]hexane 3-oxide 8 and phosphabicyclo[2.2.1]heptene 7-oxides 10 and 12 were efficiently converted to phosphine–boranes 2, 9, 11 and 13, respectively, under relatively mild conditions by reaction with 4.4 equivalents of dimethyl sulfide–borane. The more strained hetero-ring the starting phosphine oxide (in general 16) has, the easier to accomplish the change in the P-function, that takes place through the corresponding phosphine intermediate (20). It is noteworthy that the imide carbonyl groups in starting materials 10 and 12 were fully reduced by the borane to give 11 and 13 respectively.

The Dual Reactivity of 1-(2,4,6-Trialkylphenyl)phospholes Having a Flattened P-Pyramid

The trialkylphenylphospholes (1) with significant aromatic character due to the flattened P-pyramid1 displayed a dual reactivity; they could be involved in both Diels-Alder reaction with N-phenyl maleimide and in aromatic electrophilic substitutions involving Friedel-Crafts reaction with carboxylic acid chlorides to give products 2 and 3, respectively. A novel phosphorylation of the phospholes (1) through reaction with phosphorus tribromide led to a 2or a 3-substitution selectively affording products 4 or 5. The new phospholes were tested as ligands in the hydroformylation of styrene.