Ugi/xanthate cyclizations as a radical route to lactam scaffolds

The combination of Ugi reaction and xanthate radical cyclization onto alkenes allows an easy access to various highly functionalized heterocycles. The addition of chloroacetic acid to primary amines, aldehydes and isocyanides in methanol followed by the treatment with potassium ethyl xanthate, affords the xanthate Ugi adducts in good yields. These adducts were then submitted to radical cyclization conditions with dilauroyl peroxide as initiator. The choice of an alkene function properly located on the amine or the aldehyde permits the formation of 5- to 8-membered rings in moderate to good yields. (c) 2006 Elsevier Ltd. All rights reserved.