Dithioacetals from alkynes

Another route involves a palladium-copper-catalyzed tandem carbon-carbon formation/cycloaddition sequence (Equation 12) <2005TL8531>. Notably, cycloadditions of azide to the internal alkynes failed under click chemistry reaction conditions <2003DDT1128>. Cyclization under oxidative conditions has been reported from dithioacetal 163 (Equation 13) <1996TL3925>. The formation of 164 as a single diastereoisomer has been explained by stereoelectronic effects. 

Cyanogen Iodide (ICN) has been used extensively for the cyanation of alkenes and aromatic compounds [12], iodination of aromatic compounds [13], formation of disulfide bonds in peptides [14], conversion of dithioacetals to cyanothioacetals [15], formation of trans-olefins from dialkylvinylboranes [16], lactonization of alkene esters [17], formation of guanidines [18], lactamization [19], formation of a-thioethter nitriles [20], iodocyanation of alkenes [21], conversion of alkynes to alkyl-iodo alkenes [22], cyanation/iodination of P-diketones [23], and formation of alkynyl iodides [24]. The products obtained from the reaction of ICN with MFA in refluxing chloroform were rrans-16-iodo-17-cyanomarcfortine A (14)... 

Dithioacetals react with [Cp3Ti P(OEt)3 2] to produce [Cp2Ti(SR)2] and an alkylidene species [Cp2Ti=C(R )(R )] which is an excellent entry to the Wittig-type reactions from carbonyl, alkene, and alkyne substrates [59]. 

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