Alkene amino-sulfonation

Amino-sulfonation of alkenes has been performed in a three-component reaction with S03-dimethylformamide complex (SO3 DMF) and acetonitrile followed by hydrolysis.912 Whereas amino-sulfonation occurs without the use of triflic acid, the acid accelerates the reaction considerably and prevents the formation of byproducts. The X-ray structure of intermediate 282 provided evidence that the addition is completely regio- and stereoselective [Eq. (5.338)]. 

From oxidative cleavage of 1,2-diols and 1,2-amino alcohols Dibutyltin oxide, 95 By reaction of alkyl halides with sulfur-stabilized carbanions Methylthiomethyl p-tolyl sulfone, 192 From reduction of carboxylic acids Vilsmeier reagent, 341 From terminal alkenes by addition reactions... 

A second application of the use of Lewis acid catalysis in the Julia coupling can be found in the synthesis of trans-Biiktnt isosteres of dipeptides (478 Scheme 62). Initially, attempts to couple aldehydes derived from amino acids (473) resulted in poor overall yield of the alkene. This difficulty was solved by reversing the substituents, and introducing the amino acid portion as the anion of sulfone (476) to the chiral aldehyde (477). The dianion of the sulfone was formed and to it were added 2 equiv. of aldehyde and 1 equiv. of diisobutylaluminum methoxide. The resulting p-hydroxy sulfone was t en on to the reductive elimination step to produce the desired ( )-alkene (478), in 74% overall yield. 

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