Hydrophosphination of Unactivated Alkenes, Dienes and Alkynes: A Versatile and Valuable Approach for the Synthesis of Phosphines

Abstract

The last years have seen many advances in the field of organometallic catalysis. Motivating much of the work has been the potential for discovering new catalytic reactions, which can be used for the synthesis of bulky chemicals and fine chemical intermediates. Since the efficiency and the selectivity of the catalyst mainly rely on the structure of the ligand, there is a great interest in the design and the synthesis of new ligands (amines, aminoalcohols, thioether, phosphines etc). From all of them, phosphine derivatives are the most widely used with transition metal catalysts. Different approaches have allowed to prepare phosphine derivatives: nucleophilic substitution of a P-chloro derivative, nucleophilic substitution using metal phosphide, C-P cross coupling etc. A greener way to phosphines is the addition of a P-H bond to a multiple bond since no atom loss is observed (atom economy concept). These reactions are mainly carried out in the presence of radical initiators or under basic conditions. Acidic and neutral media were also proposed. A few recent examples reported the use of a metal activation. This review is designed to remember some of the early aspects of hydrophosphination reactions using phosphines, protected or not, and unactivated or slightly activated alkenes, dienes and alkynes and to focus on the more promising results obtained in this field for the last 15 years. The reactions involving pentavalent phosphorus derivatives (phosphine-oxide, thiophosphines, phosphonate and phosphate derivatives etc.) are not concerned b y this chapter.

Stepwise Expansion of a Cp* Ring at Pentelidene Complexes and Stereoselective Formation of Triphosphines

“…The intramolecular hydrophosphination of 2 b is unusual, as only intermolecular hydrophosphination reactions into unactivated or weakly activated CÀC double bonds are known; these reactions are mainly induced by radical initiators or take place under basic conditions. [11] Furthermore, another primary phosphine was used in this reaction protocol. By monitoring the reaction of H 2 PPh with [Cp*P{W(CO) 5 } 2 ] (1 a) in toluene by 31 P NMR spectroscopy between À70 and À35 8C, an adduct 2 c (Scheme 1) is detected showing the expected two doublets at d = À17.7 and À24.8 ppm (…”

P-Chirogenic silylphosphine-boranes: synthesis and phospha-Michael reactions

“…The structure of 19a is chiral and exhibits a C 2 crystallographic axis spanning the ring and both (boranato)diphenylphosphino groups, which are in trans relative configuration (Figure 1). (14), N-C1-C2-P -100.70(12), C1-C2-P-C13 -163.77 (12). C2-C1-N-C1 i -7.28 (8).…”

“…10 Usually, the stereoselective synthesis of chiral organophosphorus compounds with P-C bond formation was performed using chlorophosphines or phosphides as electrophilic or nucleophilic reagents, respectively. 9,11 In the last decade, the asymmetric hydrophosphination 12,13 and phospha-Michael addition 14 have also emerged as powerful methodologies for the synthesis of functional derivatives such as chiral organophosphorus compounds, that hold promise for applications in asymmetric catalysis. In this last case, typical reactions of Michael acceptor with free secondary phosphines or their oxide, sulfur or other borane derivatives, were achieved either in basic conditions or by heating.…”

Recent Advances in Metal-Catalyzed C–P Bond Formation

“…In hydrophosphination, a P-H bond is added across a C-X multiple bond (X = C, N, O), as reviewed recently [3][4][5][6][7]. Scheme 1 shows a typical reaction of a terminal alkyne, showing the two possible regiochemical outcomes.…”

“…Addition of diphenylphospholane oxide 6 to terminal alkynes was catalyzed by Pd(PPh 3 ) 4 [13]. Although no mechanism was proposed, the Pd(Me-DuPhos)-catalyzed asymmetric hydrophosphination of an alkyne with a phosphine-borane under kinetic resolution conditions (Scheme 6) presumably involves similar insertion and reductive elimination steps [14].…”