Benzophenone Imine

Introduction

Benzophenone imine or (diphenylmethylene)amine ­(DPMA-H, 1) is a valuable reagent in organic synthesis. [1] It is a commercially available liquid which is easily prepared by addition of phenylmagnesium bromide to benzo­nitrile followed by hydrolysis with methanol [2] or by reaction of benzophenone with ammonia. [3]

Synthetic applications of 1 have been historically related to peptide chemistry, specifically as protecting group of primary amines during the preparation of optically active α-amino acids. [4] Used in conjunction with other anion-­stabilising groups, 1 provides activation for proton ­abstraction. More recently, the development of highly ­efficient tin-free palladium-catalysed amination methodologies by the groups of Buchwald [5] and Hartwig [6] ­increased its synthetic utility as convenient ammonia ­surrogate in catalysed coupling reactions.

References

• 1 Paquette LA. Encyclopaedia of Reagents for Organic Synthesis   Vol. 1:  John Wiley; Chichester, UK: 1995.  p.293 
• 2 Pickard PL. Tolbert TL. Org. Synth., Coll. Vol. V  1973,  520 
• 3 Verardo G. Giumanini AG. Strazzolini P. Poiana M. Synth. Commun.  1988,  18:  1501 
• 4 O’Donnell MJ. Aldrichimica Acta  2001,  34:  3 
• 5 Guram AS. Rennels RA. Buchwald SL. Angew. Chem., Int. Ed. Engl.  1995,  34:  1348 
• 6 Louie J. Hartwig JF. Tetrahedron Lett.  1995,  36:  3609 
• 7 Wessjohann L. Skattebol L. de Meijere A. J. Chem. Soc., Chem. Commun.  1990,  574 
• 8 Corey EJ. Noe MC. Xu F. Tetrahedron Lett.  1998,  39:  5347 
• 9 Ooi T. Tayama E. Maruoka K. Angew. Chem. Int. Ed.  2003,  42:  579 
• 10 O’Donnell MJ. Alsina J. Scott WL. Tetrahedron Lett.  2003,  44:  8403 
• 11 Wolfe JP. Ahman J. Sadighi JP. Singer RA. Buchwald SL. Tetrahedron Lett.  1997,  38:  6367 
• 12 Shen Q. Shekhar S. Stambuli JP. Hartwig JF. Angew. Chem. Int. Ed.  2005,  44:  1371 
• 13 Guille S. Ferry A. Billard T. Langlois BR. J. Org. Chem.  2003,  68:  8932