Alkylthio-l,3-dienes

Reaction of dialkyl disulfide with allenes is catalyzed by a rhodium-phosphine complex and trifluoromethanesulfonic acid giving ( )-2-alkylthio-l,3-dienes [78]. AuBr3-catalyzed regioselective hydrothiolation of aromatic allenes with arenethiols affords the corresponding dithioketals in good yields under mild conditions [79]. Intramolecular hydrothiolation of a-thioallenes to 2,5-dihydrothiophenes is successfully catalyzed by AuCl (Scheme 24) [80]. 

ArisawaM, Suwa A, Fujimoto K, Yamaguchi M. Transition metal-catalyzed synthesis of ( )-2-(alkylthio)alka-l, 3-dienes from allenes and dialkyl disulfides with concomitant hydride transfer. Synth. Catal. 2003 345 560-563. 

The interaction of 1,2-borylphosphinoethene with alkylthiocyan-ates gives compounds possessing the structure of 6-alkylthio-l,5,2-azaphosphoniaboratacyclohexa-3,6-dienes (185)-(189) [Eq. (137)] (92IZV-1638). 

With l-alkylthio-2-diethoxyphosphoryloxy-substituted 1,3-dienes an interesting route to racemic bicyclic a-hydroxycarbonyl compounds was found (Scheme 66) [122]. Dienes 267 [151] react readily with a number of dienophiles yielding endo products 269. Their oxidation delivered sulfoxides... 

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