Aryl(trimethylsilyl)selenides as Reagents for the Synthesis of Mono- and Diselenoesters

Silylated organoselenium reagents react under mild conditions with acid chlorides to provide a high yield route to aromatic selenoesters. The synthesis, structures, and spectroscopic properties of the selenoesters C6H5SeC(O)R (R = CH2CH3, 1; p-CH3C6H4, 2; p-C6Me4Br, 3; p-C6Me4C(O)SeC6H5, 4) and RC(O)SeFcSeC(O)R (Fc = Fe(C5H4)2; R = CH2CH3, 5; p-CH3C6H4, 6; p-BrC6Me4, 7) and RC(O)Se(C6H4)nSeC(O)R (n = 1, R = CH2CH3, 8a; n = 2, R = CH2CH3, 8b; n = 1, R = p-CH3C6H4, 9a; n = 2, R = p-CH3C6H4, 9b; n = 1, R = p-C6Me4Br, 10a; n = 2, R = p-C6Me4Br, 10b) and C6H5SeC(O)CH2CH2C(O)SeC6H5 11 are discussed. Although 11 can be prepared in high yield from the reaction of C6H5SeSiMe3 and ClC(O)CH2CH2C(O)Cl in tetrahydrofuran solvent, similar reactions in the absence of solvent led to the competitive formation of both 11 and (C6H5Se)3CCH2CH2C(O)OSiMe3 12. The new selenoesters have been characterized by multinuclear NMR (1H, 13C, 77Se), IR, and UV–vis spectroscopies, electrospray mass spectrometry, and, for complexes 2, 4, 7, 10b, and 12, single-crystal X-ray diffraction.