No abstract

No abstract

No abstract

A comparison of the reactivity of ene‐sulfides and en‐ethers towards organometallic reagents reveals some remarkable differences. With the thio compounds metallation at the olefinic site next to the hetero atom dominates clearly over the alternative deprotonation of an allylic position. Only with propenyl phenyl sulfide both exchange modes were observed simultaneously, whereas with all higher homologues of it as well as vinyl phenyl sulfide the metal was exclusively attached to the olefinic α‐carbon atom.

1,4-Dienes, vinyl ethers, allyl ethers, allyl thioethers and propene-thiolates are efficiently metalated by butyllithium in the presence of an activator such as potassium t-butoxide. Since the solvent, the counter-ion or the temperature may be varied before subsequent treatment with an electrophilic reagent, the critical ratio of direct us. vinylogous attack (substitution a t the K-or y-position, respectively) can usually be adjusted within large limits. In many cases stereoselectivity is achieved as well.

No abstract

No abstract

No abstract