Ylids startg

H)-Furanones from /-ketosulfo-nium ylids. Startg. triketosulfonium ylid refluxed 1 hr. in benzene 2-acetyl-5-phenyl-3(2H)-furanone. Y ca. 100%. 

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). 

Startg. diketosulfonium ylid treated at room temp, with Zn and acetic acid in dioxane -> 6-phenylhexan-2,4-dione. Y 82%. F. e. s. 

Ester- and nitrile-stabilized ylid anions are more reactive than the corresponding neutral ylids and react with ketones (even enolizable ones) as well as aldehydes. E a,p- thylenecarboxylic acid esters. 2 eqs. BuLi (in hexane) added to a stirred suspension of startg. diphenylphosphonium bromide in THF, 1 eq. acetone added, and stirring continued at room temp, for 30 min product. Y 43% (Y 10% using 1 eq. BuLi and 0% with PhjP = CHC02Me). F.e. incl. a,p-ethylenenitriles, and trans stereo-selectivity with aldehydes, s. E.G. McKenna, B.J. Walker, J. Chem. Soc. Chem. Commun. 1989, 568-9 (E)-stilbene s. Tetrahedron Letters 29, 485-8 (1988). 

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). 

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). 

Cumyl hydroperoxide added at room temp, to a soln. of the startg. ylid in methylene chloride, and the product isolated after 24 hrs. product. Y 64%. F. e. s. V. Sniedcus and G. Kan, Tetrah. Let. 1970, 2267. 

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

---