Here we wish to report a convenient alternative synthesis of the diazospiro system by adding trimethysilyl cyanide to (1a) in the presence of catalytic amounts of zinc iodide to give the adduct 2iodide to give the adduct (2）(7,8), which was reduced with LAH to give the amino alcohol (3), and subsequently ring closed with triphosgene to give the desired compound (4a) in 72% yield from (3). Using the same technique we also converted 1- (2-phenylethyl)-4-piperidone (1b) to Fenspiride (4b),a bronchodilator blocker (9,10).
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