2- benzothiazole, reaction with metal carbonyls

Compounds with a variety of functional groups can be synthesized from arsine oxides by metalation and reaction with electrophilesS subsequent reduction and replacement of the arsenic group by nucleo-philes. Benzothiazoles have been used as versatile carbonyl equivalents, which react under very mild conditions one or two C-branches can be attached stereoselectively and annelation of fused and spiro rings has been described . 

Sylvestre Julia and co-workers discoveried in 1991 a direct synthesis of olefins by reaction of carbonyl compounds with lithio derivatives of 2-[alkyl- or (2 -alkenyl)- or benzyl-sulfonylj-benzothiazoles (BT, 5). Since the initial study of the reaction of metallated BT sulfone 5 with carbonyl compounds, the versatility of these derivatives has been fully demonstrated through their application in the total synthesis of a large number of nature products. Kocienski and co-workers found in 1998 that l-phenyl-17/-tetrazol-5-yl sulfone (PT, 6) is a better olefination partner comparing to BT sulfones. This allowed the one-port Julia-Lythgoe olefination to be employed more efficiently and broadly, especially in the synthesis of nature products. 

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