The alcohol may also be dehydrated to the olefin by treatment with acids such as p-toluenesulfonic acid. [0218] Compounds of the formula II, wherein R1 is G2 and R6 is hydrogen, can be converted into the corresponding compounds of the formula II, wherein R1 is G2 and R6 is other than hydrogen, by reacting them with a compound of the formula R6L???, as described above in Scheme 1, for preparing com