Sulfones, vinyl amino synthesis

Thiazoles, vinyl-radical polymerization, 6, 278 Thiazole-5-sulfonic acid, 2-amino-synthesis, 6, 255-256 Thiazole-2-sulfonic acids reactions, 5, 104 6, 291 Thiazole-5-sulfonic acids synthesis, 6, 255 Thiazole-5-thione, 2-phenyl-tautomerism, 6, 249 Thiazolethiones reactivity, 6, 250 Thi azole-2-thiones reactions, 5, 102 tautomerism, 5, 367 Thiazolidine, 2-alkyl-occurrence, 6, 327 Thiazolidine, 2-arylimino-X-ray analysis, 6, 238 Thiazolidine, 4-imino-mesoionic didehydro derivative nomenclature, 1, 34 nomenclature, 1, 34... 

The synthesis of the preceding vinyl amino sulfone offers a very good example of a stereospecific sulfide-directed epoxidation (Scheme 76).Oxidation of optically active sulfide alcohol (12 readily made from epoxycyclopentadiene and resolved) with MCPBA affords the corresponding sulfoxide, which is in equilibrium with the sulfenate ester. Treatment with pyridine hydrobromide and then phenyl disulfide and bromine gives the bromodiol (13), which is simply cyclized to the epoxide with aqueous sodium hydroxide solution (83% overall yield from the sulfoxide). Treatment of the P-epoxy sulfone with DBU followed by in situ silylation with f-butyldiphenylsilyl chloride affords an 86% yield of vinyl sulfone (14). Mesylation of the alcohol moiety followed by immediate treatment with dimethylamine produces the amino vinyl sulfone via a syn Sn2 substitution. ... 

Most immobilization methods require modification of the ligands for anchoring to the support by introducing functional groups such as vinyl, trialkoxysilyl, sulfonic acid, and amino groups. The consequence is often a more elaborate synthesis of the ligand, which adds to the costs of an immobilized catalyst. However, two interesting approaches were developed in recent years, when unmodi-... 

Vinyl sulfones are superior to the sulfoxides (see Section 7.3.1.2.2.) for the diastereoselective synthesis of / -hydroxy-a-amino acids via intramolecular conjugate addition of a carbamate nitrogen. 

Exactly the same method was successfully employed in the synthesis of 2,2 -bipyridines bearing a free amino group. Thus 4,4 -diamino-2,2 -bipyridine was prepared from 5-amino-2-chloropyridine in 60% yield, respectively [38]. Nickel-catalysed synthesis of biaryls and related vinyl halides were successfully used in a great number of examples [39,40], including the strained aromatic ether-sulfone oligomers [41]. For instance, compound 84 was cyclized to a very strained cyclic... 

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