159771-73-0Relevant academic research and scientific papers
Organic syntheses via transition metal complexes. 75. Phosphinonaphthalenes and phosphinoindenes by cyclization of alkynyl carbene complexes (M = Cr, W)
Aumann, Rudolf,Jasper, Beate,Fr?hlich, Roland
, p. 231 - 237 (2008/10/08)
1-Amino-2-ethoxy-4-phosphinonaphthalenes 6a,b (>90% yields) are obtained from (phenylalkynyl)carbene complexes (CO)5M=C(OEt)-C≡C-Ph (M = Cr, W) 1 by a novel two-step carbene/alkyne benzannulation. The first step involves the formation of (E)-(2-phenyl-2-phosphinoethenyl)carbene complexes (CO)5M=C(OEt)-CH=C(Ph)-PR2 (E)-3a-c by 3-addition of secondary phosphines HPR2 (R = t-Bu, c-C6H11) 2a,b to 1. A subsequent addition of isocyanides R1NC (R = t-Bu, c-C6H11) 4a,b to (E)-3a-c yields ketene imine complexes (CO)5M[R1N=C=C(OEt)-CH=C(Ph)-PR2] A by the insertion of 4 into the M=C bond of 3. (Metal-free) ketene imines are generated from A by ligand displacement with 4 and cyclize spontaneously to 6. Thermolysis of (E)-3a-c affords (CO)5M phosphinoindene complexes 9 and 10. Reaction of 9 or 10 with pyridine yields phosphinoindenes 12 and pyridine complexes (CO)5M(C5H5N) 11. 10a, C24H29CrO6P, was characterized by X-ray diffraction. It crystallizes in space group P1 No. 2 with cell parameters a = 9.412(1) ?, b = 11.455(2) ?, c = 11.962(2) ?, = 89.10(1)°, β = 79.09(1)°, γ = 88.60(1)°, Z = 2, R1 = 0.063, and wR2 = 0.117.
