in diethyl ether refluxing for 2.5 h;;

sodium hydroxide; water; dihydrogen peroxide in tetrahydrofuran; water to soln. of Sn compd. in THF added soln. of BH3 (B/Sn ratio 1/1) in THF under N2 at room temp., stirred 1 h, refluxed 1h, cooled to room temp., added H2O, added soln. of 3 M NaOH in 30percent H2O2, stirred for 30 min; added Et2O, extd. (3 M NaOH), acidified with dil. HCl, extd. (Et2O);

in not given byproducts: C6H6;