Abstract
Sequential treatment of CpW(CO) 3 (CH 2 C=CCMe=CH 2 ) (1) with CF 3 SO 3 H and MeOH in cold diethyl ether (-40°C) gave a 75% yield of CpW(CO) 3 (η 3 -anti-2-CO 2 Me-4-methylpentadienyl) (2). Compound 2 reacted with TCNE to afford the novel [5 + 2] cycloaddition adduct 3 in 62% yield; the molecular structure of 3 showed a 1,2-shift of the tungsten fragment, indicating a η 4 -s-cis-diene reaction intermediate. The reaction of 2 with reactive isocyanates RN=C=O (R = PhSO 2 , CH 3 C 6 H 4 SO 2 ) in cold CH 2 Cl 2 produced 4a (R = PhSO 2 ) and 4b (R = CH 3 C 6 H 4 SO 2 ) in 82% and 87% yields, respectively; the two compounds can be regarded as the acylation derivatives of 2, according to an X-ray diffraction study of 4a.