Organometallic chemistry of sulfinic acids. Highly stereo- and regioselective intramolecular hydroplatinations. X-ray crystal structure of (Ph3P)2Pt[trans-SO2CH(CH3)CH 2CH(CH2CH3)]

Article abstract of DOI:10.1021/om00102a010

Reactions of sulfinic acids with platinum(0) and platinum(II) complexes are described. p-Tolylmethanesulfinic acid reacts with tetrakis(triphenylphosphine)platinum, (Ph₃P)₄Pt, to afford trans-(Ph₃P)₂Pt(H)SO₂R (R = CH₂-p-tolyl) in 70% yield. (COD)Pt(CH₃)SO₂R (COD = 1,5-cyclooctadiene; R = CH₂-p-tolyl, 77% yield), (COD)Pt(CH₃)SO₂R (R = p-tolyl, 53% yield), and cis-(Ph₃P)₂Pt(CH₃)SO₂R (R = p-tolyl, 91 % yield) were prepared analogously from the corresponding L₂PtMe₂ complexes. Treatment of cis-(Ph₃P)₂Pt(CH₃)₂ with butene-4-sulfinic acid and pentene-4-sulfinic acid afforded isomerically pure chelates (Ph₃P)(CH₃)Pt(η³-SO₂CH(R)CH ₂CH₂CH≡CH₂) (R = H, 33% yield; R = CH₃, 31% yield). Reaction of cis-(Ph₃P)₂Pt(CH₃)₂ with hexene-5-sulfinic acid afforded the unchelated derivative (Ph₃P)₂(CH₃)Pt(η¹-SO ₂CH(CH₃)CH₂CH₂CH ₂CH=CH₂) (22% yield). Intramolecular hydrometalations were observed upon treatment of (Ph₃P)₄Pt with unsaturated sulfinic acids. Butene-4-sulfinic acid was converted to (Ph₃P)₂PtSO₂CH₂CH ₂CH(CH₃) (69% yield). Pentene-5-sulfinic acid afforded metallacyclohexane (Ph₃P)₂PtSO₂CH₂CH₂CH ₂CH(CH₃) (37% yield), which upon heating, isomerized to a metallacyclopentane, (Ph₃P)₂PtSO₂CH₂CH ₂CH(CH₂CH₃), in 27% yield. Pentene-4-sulfinic acid afforded (Ph₃P)₂Pt[CJs-SO₂CH(CH₃)CH ₂CH(CH₃)] (37% yield, >20:1 stereoselectivity), which upon heating afforded (Ph₃P)₂Pt[trans-SO₂CH(CH₃)CH ₂CH(CH₃)] in 56% yield and >20:1 stereoselectivity. Hexene-5-sulfinic acid afforded the metallacyclohexane (Ph₃P)₂PtSO₂CH(CH₃)CH ₂CH₂CH(CH₃) (47% yield) as a cis/trans mixture of unassigned stereochemistry. Upon heating, both isomers isomerized to (Ph₃P)₂Pt[trans-SO₂CH(CH₃)CH ₂CH(CH₂CH₃)] in 36% yield and >20:1 stereoselectivity. Stereochemical assignments of all metallacyclopentanes derived from a molecular structure determination of (Ph₃P)₂Pt[trans-SO₂CH(CH₃)CH ₂CH(CH₂CH₃)]. The metallacycle crystallized in P2₁/c space group with cell parameters a = 10.563 (1) A?, b = 9.733 (17) A?, c = 36.362 (42) A?, β = 94.59°, Z = 4, and R_w = 9.8%. Attempts to deinsert SO₂ from the platinum sulfinates failed to afford the corresponding metal alkyls.