Sulfides, allyl 2-pyridyl

Pyridyl allyl sulfide, on the other hand, gives only one regioisomer in its alkylation reactions. U lsensible here to show the allyl anion as a compound with a C-Li bond. 

Lithiated allyl sulfides (in common with allyl sulfoxides and selenides, but in contrast with allyl ethers and allyl amine derivatives) tend to react with alkyl halides at the a position, adjacent to S.1 The best a-selectivities are obtained with lithium-coordinating S-substituents such as pyridyl (114),85 imidazolyl (115), and dimethylaminocarbonyl (116).1... 

When favorable results in the case of allylic sulfones had been obtained, asymmetric synthesis of the cyclic sulfides 5a, 5ba, Sab and Sea (Scheme 2.1.4.9) and of the acyclic sulfides 6aa, Gab, 6ac, 6ba, and 6bb (Scheme 2.1.4.10) was investigated. As shown by Table 2.1.4.9, the pyrimidyl sulfide Saa could be obtained in medium to good yield (entry 1). Interestingly, the corresponding pyridyl sulfide Sab isolated from the reaction of rac-laa with 2-pyridinethiol had a much lower ee value (entry 2). The reaction of the cycloheptenyl carbonate rac-lba with 2-pyrimi-dinethiol afforded the sulfide Sba in a similar yield to the cyclohexenyl derivative... 

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