Stereoselective Synthesis of 3,4-trans-Disubstituted γ-Lactams by Cerium(IV) Ammonium Nitrate Mediated Radical Cyclization of Cinnamamides

Abstract

A facile synthesis of 3,4-trans-disubstituted γ-lactams was developed, consisting of the radical cyclization of cinnam­amides mediated by cerium(IV) ammonium nitrate. The single-electron-transfer (SET) reaction of the methoxystyrenyl moiety mediated by cerium(IV) ammonium nitrate gives rise to a cation radical, whose cyclization followed by reaction with oxygen and methanol generates 3,4-trans-disubstituted γ-lactams.

Key words

cerium(IV) ammonium nitrate - intramolecular cyclization - cinnamamides - single electron transfer - γ-lactams

References

• 1a Imamoto T. Lanthanide Reagents in Organic Synthesis   Academic Press; London: 1994. 
• 1b Hwu JR. Curr. Sci.  2001,  81:  1043 
• 1c Ho T.-L. Paquette LA. Encyclopedia of Reagents for Organic Synthesis   Wiley; Chichester: 1995.  p.1027 
• 2a Nair V. Mathew J. Radhakrishnan KV. J. Chem. Soc., Perkin Trans. 1  1996,  1487 
• 2b Nair V. Mathew J. Prabhakaran J. Chem. Soc. Rev.  1997,  127 
• 2c Nair V. Treesa PM. Maliakal D. Rath NP. Tetrahedron  2001,  57:  7705 
• 3 Nair V. Balagopal L. Rajan R. Mathew J. Acc. Chem. Res.  2004,  37:  21 
• 4 Nair V. Panicker SB. Nair LG. George TG. Augustine A. Synlett  2003,  156 
• 5a Molander GA. Chem. Rev.  1992,  92:  29 
• 5b Narasaka K. Okauchi T. Tanaka K. Murakami M. Chem. Lett.  1992,  2099 
• 5c Narasaka K. Arai N. Okauchi T. Bull. Chem. Soc. Jpn.  1993,  66:  2995 
• 5d Linker T. Sommermann T. Kahlenberg F. J. Am. Chem. Soc.  1997,  119:  9377 
• 6a Takemoto Y. Ibuka T. Tetrahedron Lett.  1998,  39:  7545 
• 6b Snider BB. Kwon T. J. Org. Chem.  1990,  55:  4786 
• 6c Durand A.-C. Dumez E. Rodriguez J. Dulcere J.-P. Chem. Commun.  1999,  2437 
• 6d Baciocchi E. Paolobelli AB. Ruzziconi R. Tetrahedron  1992,  48:  4617 
• 6e Wang L. Seiders JR. Floreancig PE. J. Am. Chem. Soc.  2004,  126:  12596 
• 7a Nair V. Balagopal L. Sheeba V. Panicker SB. Rath NP. Chem. Commun.  2001,  1682 
• 7b Nair V. Mohanan K. Suja TD. Suresh E. Tetrahedron Lett.  2006,  47:  2803 
• 8a Nair V. Balagopal L. Rajan R. Deepthi A. Mohanan K. Rath NP. Tetrahedron Lett.  2004,  45:  2413 
• 8b Nair V. Mohanan K. Suja TD. Suresh E. Tetrahedron Lett.  2006,  47:  705 
• 9a Tchissambou L. Benechie M. Khuong-Huu F. Tetrahedron  1982,  38:  2687 
• 9b Nilsson BM. Ringdahl B. Hacksell U. J. Med. Chem.  1990,  33:  580 
• 9c Bergman R. Gericke R. J. Med. Chem.  1990,  33:  492 
• 9d Garvey DS. May PD. Nadzan AM. J. Org. Chem.  1990,  55:  936 

10

The difference between the coupling constants for the benzylic protons in 2a (4.2 Hz) and 2a′ (2.4 Hz) indicates that the isomeric pair 2a and 2a′ differs only in the relative stereochemistry of the methoxy group at the benzylic position.