This is a very revolutionary reaction! I don't know how the f*ck they discovered it, but by monotosylating a diol, you can substitute the tosyl group with a cyanide, add a grignard reagent to the resulting nitrile to make a ketone, then REDUCE THE KETONE TO AN ALDEHYDE BY CLEMMENSEN REDUCTION TO GET AN ALCOHOL WITH THE CARBON CHAIN EXTENDED BY THE LENGTH OF THE DIOL PLUS ONE!!!!!!!!!!!!!!!@@@@@@@@!!!!!!!!@!@@@!!!!!