... The Journal of Organic ... Table 1. Synthesis of β,β-Disubstituted Vinylic Sulfoxides with Et 2 Zn a. entry, catalyst (mol %), Et 2 Zn b (mol per 1 mol of 1a), concn (M), yield (%). 1, CuI (2), 1, 0.1, 15. 2, CuI (2), 2, 0.1, 72. 3, CuI (2), 4, 0.1, 57. 4, CuI (0.5), 2, 0.1, 35. 5, CuI (10), 2, 0.1, 46. 6 ...