Control of sulfur neighbouring group participation exploited in a general synthesis of piperidines

ORGN 375

Mairi Gibson, Louis J. Farrugia, and Richard C. Hartley. Department of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
Thioacetals are useful intermediates in organic synthesis and are often used as masked carbonyl groups. Recently, we have been interested in thioacetals as substrates for the generation of titanium alkylidenes in the synthesis of heterocycles.

Whilst trying to prepare azide 3 from alcohol 1, we found that a 1,3-dithiane 2 displaces tosylate by 5-exo-tet cyclisation to give bicyclic sulfonium salt 4. Nucleophilic attack on this 4-thia-7a-thioniaperhydroindene 4 by azide ions kinetically favours opening to give a nine-membered a-azidosulfide 6.

However, neighbouring group participation can be controlled, and we here report the successful preparation of azide 3 (via sulfonium salt 5) and its subsequent use in a diversity based solid phase synthesis of 2-substituted piperidines 7.

 

Physical Organic, Materials, Heterocycles, Aromatics, Metal-Mediated Reactions
8:00 PM-10:00 PM, Tuesday, September 9, 2003 Hilton New York -- Americas Hall 1, Poster

Division of Organic Chemistry
The 226th ACS National Meeting, New York, NY, September 7-11, 2003