Sulfonium startg

Startg. sulfonium salt allowed to react with NaH in tetrahydrofuran thioether. Y 90-95%. F. e. s. G. M. Blackburn et al., Chem. Commun. 1968, 186. 

NOCl bubbled at -20° during 10 min. into a stirred soln. of the startg. enamine in chloroform, stirring continued 0.5 hr. at -20°, then a soln. of the startg. sulfonium ylid in diloroform added dropwise with stirring and allowed to warm to room temp, overnight product. Y 74%. - Isoxazoles not easily accessible otherwise can be obtained by this method. F. e. s. P. Bravo and C. Ticozzi, G. 105, 91 (1975). 

A soln. of startg. sulfonium salt in acetone added slowly over 2 days to a stirred suspension of K2CO3 in the same solvent under reflux -> product. Y 86%. F.e. and regiospecific conversion of 2-alkylthiophanium analogs, also macrocyclic lactones from diphenylsulfoniocarboxylic acids, s. H. Matsuyama et al., Chem. Letters 1988, 1931-2. 

A soln. of startg. diazoester and freshly prepared Rh(ll)-acetate in benzene stirred for 10 min at room temp., and heated for 20 min at 80° - product. Y 68%. [2.3]-Sigma-tropic rearrangement via an 8-membered sulfonium ylid appears to be unprecedented. F.e.s. F. Kido et al.. Tetrahedron Letters 30, 1575-8 (1989). 

A soln. of the startg. sulfonium salt in abs. ethanol added dropwise with icecooling to a stirred mixture of ethyl acetoacetate and Na-ethoxide in abs. ethanol, and the product isolated after 5 hrs. -> 9-ethoxycarbonyl-8-methyl-7-oxabicyclo-[4.3.0]-8-nonen-5-one. Y 91-98%. F. e. s. T. Mukaiyama, T. Adadii, and T. Kumamoto, Bull. Chem. Soc. Japan 44, 3155 (1971) furans from 2-acetylenesulfo-nium salts cf. J. W. Batty, P. D. Howes, and C. J. M. Stirling, Soc. Perkin I 1973, 65. 

Startg. diazo ester allowed to react at 80° with dimethyl sulfoxide in the presence of Cu-powder product. Y 93%. F. e., also with AggO as catalyst, s. F. Dost and J. Gosselck, Tetrah. Let. 1970, 5091 preferably with CuCN as catalyst s. B. i 5, 948 (1972) also sulfonium ylids from thioethers in the presence of CUSO4 or by irradiation with 3660 A light of a high-pressure Hg-lamp s. W. Ando et al., J. Org. Chem. 37, 1721 (1972). 

Startg. sulfonium fluoroborate warmed several hrs. with an equimolar amount of Na-ethoxide in abs. ethanol ethyl 2-phenyl-5,6-dihydro-4H-pyran-3-carboxy-late. Y 86%. F. e. s. J. Gosselck and A. Winkler, Z. Chem. 10, 380 (1970). 

Startg. cyclic sulfonium perchlorate heated at 90° with l,8-diazabicyclo[5.4.0]-undec-7-ene in toluene cw-product. Y 67% (and 7% rran -isomer). - S-Macro-heterocyclics by repetition of this 2,3-sigmatropic shift s. E. Vedejs and J. P. Hagen, Am. Soc. 97, 6878 (1975). 

Startg. sulfonium ylid allowed to react at room temp, with -toluenesulfonyl chloride in tetrahydrofuran containing excess triethylamine ethyl trans-... 

---