Highly Atom-Economic One-Pot Formation of Three Different C−P Bonds:  General Synthesis of Acyclic Tertiary Phosphine Sulfides

Abstract

The reaction of benzothiadiphosphole 1 with an equimolar mixture of R1MgBr and R2MgBr gave intermediate A', which, after only 4-5 min, was treated with an equimolar amount of R3MgBr, giving the asymmetric phosphine PR1R2R3 in 45% overall yield (75-80% yield when R1 = R2 and 85-90% yield when R1 = R2 = R3) and the byproduct 6 in 90% yield. The treatment of 6 with PCl3 quantitatively regenerates the starting reagent 1. Treatment of the phosphines with elemental sulfur gave the corresponding sulfides.

The First Flights of a Molecular Shuttle Transporting Elements: Easy One‐pot Formation of Organic Cyclic Arsanes, Stibanes and Bismutanes

“…Recently, we reported [5] (Scheme 1) a new synthesis of tertiary cyclic phosphanes 2 and 3 in 60-70 % yields [5a,b] by addition of a bisA C H T U N G T R E N N U N G (Grignard) reagent and a Grignard reagent to an unusual phosphorus-donor reagent, the benzothiadiphosphole 1 a, [6] called by us a "butterfly reagent" [7] owing to its particular folded structure. At the end of the reaction the starting reagent 1 a was quantitatively regenerated by addition of one equivalent amount of PCl 3 to the end-product 4, which is the remainder of 1 a obtained after quenching the reaction mixture with water (Scheme 1).…”

General and Efficient One‐Pot Synthesis of Tertiary Phosphane–Borane Complexes Containing Different Alkyl Groups and In Situ Facile Recycling of the Phosphorus Donor Reagent

“…For this purpose, we carried out the reaction between compound 1 and 3 equiv. of the Grignard reagent (as previously reported [25] to obtain acyclic tertiary phosphanes) and then we directly treated the reaction mixture containing the phosphanes 5a,b with BH 3 ·THF. In this manner, tertiary phosphaneborane complexes 6a,b were obtained in high yields (85-90 %) without isolation of the free phosphanes (Scheme 2).…”

“…The formation of such intermediates is favoured by the "dibenzo-butterfly" structure of 1, as we reported for the synthesis of cyclic tertiary phosphanes. [31] It is noteworthy that previously [25,31] we thought that the hexacoordinate intermediate AЈ required a nucleophilic attack, for example, by water or an acid in order to decompose it. During this study, however, we observed by 31 P NMR spectroscopy that AЈ is unstable and spontaneously collapses to give the corresponding tertiary phosphanes, presumably due to its high steric hindrance.…”

“…[24] The intermediate involved in the synthesis of the phosphanes 2 from 1 might be a hypervalent phosphorus species such as A, as reported elsewhere. [25] We also reported a new efficient method for the synthesis of borane complexes 4 (70-85 % yield) of the secondary phosphanes 2 by simple treatment of the reaction mixture with acetic acid followed by the in situ addition of the BH 3 ·THF complex. [22] Surprisingly, we found that the secondary phosphane 3 was not complexed by BH 3 ; this finding is of fundamental importance because it enables the recycling of 3.…”

Unusual reaction of 8-chloro-2-cyclohexyl-4-phenylbenzo[e]-1,2-oxaphosphinine-2-oxide with tetramethylenebis(magnesium bromide)

“…Achiral (R 3 P=O), prochiral (R 2 R 1 P=O) and chiral (R 1 R 2 R 3 P=O) phosphine oxides are the main precursors in the syntheses of corresponding phosphines, [1][2][3][4][5][6][7][8][9][10][11] which are widely used as ligands in metal complex catalysts 2,4,6,10,12 and neutral extracting agents for rare-earth metals. [13][14][15][16][17] Phosphine oxides can also be used as ligands in reactions catalysed by palladium and molybdenum complexes.…”