5.5.1 Sulfur Compounds

Organosulfur compounds find wide applications in organic synthesis. Following are the some of the important applications.

5.5.1.1 Sulfur Ylides

Sulfur ylides have numerous applications in organic synthesis. Among them, diemthylsulfonium methylide (unstabilized) and dimethyloxosulfonium methylide (stabilized) are extensively used in organic synthesis. These reagents are called Corey-Chaykovsky reagents.

J. S. Ng, C. Liu, Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons, Inc., L. A. Paquette, Ed., New York, 1995, 7 , 5335.

They exhibit different reactions with α,β-unsaturated carbonyl compounds. The former afford epoxides and the latter give cyclopropanes (Scheme 1). In the absence of double bond, both give epoxides. The epoxide formation is kinetically favourable while the formation of cyclopropane is the thermodynamic product.

Scheme 1

 

Sulfur ylides undergo rearrangements to give valuable products (Scheme 2).

Scheme 2

Examples:

C. F. D. Amigo, I. G. Collado, J. R. Hanson, R. Hernandez-Galan, P. B. Hitchcock, A. J. Macias-Sanchez, D. J. Mobbs, J. Org. Chem. 2001 , 66 , 4327.

 

E. J. Corey, M. Chaykovsky, Org. Synth. CV5, 755.

J. S. Nag, Synth. Commun . 1990 , 20, 1193.

5.5.1.2 Oxidation

N-Chlorosuccinimide-dimethyl sulfide, prepared in situ from NCS and DMS, is used as mild oxidizing reagent in organic synthesis (Scheme 3). This reagent is called Corey-Kim reagent.

Scheme 3

R. C. Kelly, Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons, Inc., L. A. Paquette, Ed., New York, 1995, 2 , 1208.