New (aminomethyl)phosphines via selective hydrophosphination and/or phosphorus based Mannich condensation reactions

Controlled stepwise reaction of a geminal substituted alkene or primary amine group afforded a small library of new functionalised tertiary and ditertiary phosphines. Accordingly, Mannich based condensation of the commercially available disubstituted arene C 6 H 4 (NH 2 ){2-C(Me)=CH 2 } with HOCH 2 PR 2 (R 2 = Cg: 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantyl; Ph 2 ) afforded the (aminomethyl)phosphines C 6 H 4 (NHCH 2 PCg){2-C(Me)=CH 2 } L 1 and C 6 H 4 (NHCH 2 PPh 2 ){2-C(Me)=CH 2 } L 2 in approx. 60% yield. In addition to the formation of L 2 , the diphosphine L 3 was also identified and independently synthesised upon reaction of C 6 H 4 (NH 2 ){2-C(Me)=CH 2 } with two equiv. of HOCH 2 PPh 2 in CH 3 OH under reflux. Alternatively, reaction of C 6 H 4 (NH 2 ){2-C(Me)=CH 2 } with H-PR 2 (R 2 = Cg or Ph 2 ) in the presence of AIBN [2,2′-azobis(2-methylpropionitrile)] as free radical initiator, afforded the primary amine functionalised phosphines C 6 H 4 (NH 2 ){2-CH(Me)CH 2 PCg} L 4 and C 6 H 4 (NH 2 ){2-CH(Me)CH 2 PPh 2 } L 5 in 85% and 66% isolated yields respectively. In both cases only the anti-Markovnikov addition products were observed. Subsequent reaction of L 5 with HOCH 2 PR 2 (R 2 = Ph 2 ) afforded the unsymmetrical ditertiary phosphine C 6 H 4 (NHCH 2 PPh 2 ){2-CH(Me)CH 2 PPh 2 } L 6 . Some preliminary coordination studies towards [RuCl(μ-Cl)(η 6 -C 10 H 14 )] 2 [AuCl(tht)] (tht = tetrahydrothiophene) and [MCl 2 (η 4 -cod)] (M = Pd, Pt; cod = cycloocta-1,5-diene) demonstrate these new ligands behave as classic P-donors leaving the pendant amino or alkenyl groups non-coordinating. All compounds have been characterised by multinuclear NMR, FT−IR, mass spectrometry and microanalysis. Single crystal X-ray studies have been performed on L 3 , L 5 , L 6 , 1, 3b·0.5CH 2 Cl 2 , 4a·1.5CH 2 Cl 2 , 5 and 6·0.5CDCl 3 ·0.5C 4 H 10 O.