Facile Access to Bicyclic Sultams with Methyl 1‐Sulfonylcyclopropane‐1‐carboxylate Moieties

• Published in: European Journal of Organic Chemistry 2009-06, Vol.2009 (16), p.2635-2641
• Main Authors: Rassadin, Valentin A., Tomashevskiy, Aleksandr A., Sokolov, Viktor V., Ringe, Arne, Magull, Jörg, de Meijere, Armin
• Format: Article
• Language: English
• Subjects: Cyclopropanes; Intramole­cular cyclodialkylation; N‐Alkenylanilines; Oxidative deprotection
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200900113

N‐(2,3‐Dibromopropyl)‐ and N‐(3,4‐dibromobutyl)(methoxycarbonyl)methanesulfanilides upon treatment with potassium carbonate in DMF furnish methyl 3‐aryl‐2,2‐dioxo‐2‐thia‐3‐azabicyclo[n.1.0]alkane‐1‐carboxylates in yields ranging from 54 to 84 % (10 examples). The starting materials were obtained by sulfonylation of N‐alkenylanilines with methyl (chlorosulfonyl)acetate and subsequent bromination. For the N‐alkenylanilines (10 examples, 60–77 % yield) an efficient new synthesis employing a 2‐nitrophenylsulfonyl substituent as a protective as well as an activating group has been developed. The 4‐methoxyphenyl (PMP) group could easily be removed from the sultam nitrogen atom by treatment with cerium(IV) ammonium nitrate.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) Bicyclic sultams with methyl 1‐sulfonylcyclopropane‐1‐carboxylate moieties can be assembled from N‐alkenylanilines and methyl (chlorosulfonyl)acetate by way of bromine addition to the double bond andintramolecular cyclodialkylation. The 2‐nitrophenylsulfonyl group serves as a protective as well as an activating group in the preparation of the N‐allyl‐ and N‐homoallylanilines.