n-butyllithium; isopropylamine in dichloromethane C4H9Li + i-C3H7NH2/THF (N2, 0°C); + (C4H9)3SnH (0°C, 30min), cooled to -78°C, + aldehyde, stirred (10min), + NH4Cl, extn. (Et2O), washed, dried (MgSO4), evapd.; residue dissolved in CH2Cl2, + t-C4H9SiMe2Cl, Et3N and 4-Me2N-pyridine; soln. stirred overnight, washed (1 M NH4Cl), dried (MgSO4), evapd.; flash chromy. (silica gel, pentane);

in tetrahydrofuran dropwise addn. of aldehyde to a THF soln. of stannyl anion (-78°C), stirring at -78°C for 15 min, quenching at -78°C by dropwise addn. of the trialkylsilylcyanide, warming to room temp., stirring for 1 h; diluting with petroleum ether, washing with satd. aq. NaCl, drying over anhyd. Na2SO4, removing solvents under reduced pressure yields crude stannyl silyl ether;