Thiazetidines reactivity

A sulfonylimine that is formed in situ as a reactive intermediate by interaction of the corresponding aminosulfonyl chloride and triethylamine has proved to be a popular cycloaddition reagent in the synthesis of 1,1-thiazetidines. 

Experimental reactivity and mechanistic studies on the solvolysis of /3-sultams have shown that opening of the S-N bond produced a sulfonic acid or sulfonate ester and that there was no evidence of C-S fission. Alcoholysis of A-methyl-1,2-thiazetidine 1,1-dioxide 11 was investigated using ab initio calculations and density functional theory... 

Reactivity of Substituents Attached to Ring Heteroatoms 2.15.7.1 1,2-Thiazetidine 1,1 -Dioxides... 

Concerning the reactivity of /3-sultams, it was recently demonstrated that thermolysis of a pentacoordinate 1A6,2-thiazetidine gave the corresponding aziridine and a cyclic sulfinate almost quantitatively. The potential intermediacy of lA6,2-thiazetidine was suggested in this aza-Corey-Chaykovsky type reaction <2006OL4625>. 

The cycloaddition of A -sulfonyl amines (Af-sulfonyl imides) (e.g., 431 ) to alkenes gives 1,2-thiazetidine 1,1-dioxides. " The stereochemistry about the double bond of the alkene is preserved in the adduct, and a tight zwitterionic intermediate is favored. Considerable amounts of six-membered cyclic adducts also are formed in these additions. Yields vary from good to poor. Thermolysis of 432 yields sulfonyl amine 433 the higher reaction temperatures involving 433 enable less reactive alkenes such as cis-stilbene to be used successfully. The success of cycloadditions to enamines depends on the latter having no protons on the -alkene carbon or on an sp hybridized carbon attached to the a-position. ... 

The more reactive tosyl-, alkoxycarbonyl- and mercaptocarbonyl isothiocyanates undergo a [2+2] cycloaddition reaction with azomethines (R = i-Pr, CeHn, Ph) across their C=S bonds to give 1,3-thiazetidine derivatives 42 (R = 4-MePhS02-, MeSCO-, EtOCO-)22. 

Reactions.— The nucleophilic reactivity of the thiocarbonyl sulphur atom in thioureas has been further exemplified in a series of papers reporting on S-alkylation reactions of open-chain " as well as cyclic thioureas using alkyl halides. Ried and his co-workers have reported that (4-quinazolyl)thioureas (315) react smoothly with methylene iodide in the presence of triethylamine to yield the 1,3-thiazetidines (316). The ready formation of (316) was attributed to the special effect of the intramolecular hydrogen bonding in (315), as common thioureas usually did not enter into this reaction in a well-defined and profitable way. 5,5-Diphenyl-2-thio-hydantoin reacted with symmetrical ao>-dibromo-alkanes to yield the cyclization products (317). The action of excess of methyl iodide on N -substituted N-(o-aminophenyl)thioureas afforded the benzimidazoles (318), alternatively obtainable by treatment of the same thioureas with mercuric chloride." " In a similar manner, l-amino-6,7-dimethoxy-3,4-di-hydroisoquinolines were formed by the action of mercuric chloride on the thioureas (319)" or their S-methyl derivatives (320). " A recent paper by Klayman and his co-workers deals with the reactivity of S-methiodide derivatives of thioureas that are activated by electron-withdrawing groups towards hydroxylic compounds. "... 

---