copper (I) cyanide in not given to soln. of alkyne added (n-Bu)3SnMgMe and 5 molpercent catalyst, then treated with H3O(1+) at 0 °C for 10 min; ratio of C10H21C(SnBu3)CH2 : (C10H21)CHCH(SnBu3) 30:70; combined yield - 70percent;