(-)-Sparteine in Asymmetric Synthesis

Introduction

Asymmetric synthesis represents a challenging topic in modern organic chemistry. The asymmetric deprotonation of a prochiral carbon by a chiral base offers attractive access to a chiral carbanion, which may react to give enantioenriched products. (-)-Sparteine is a chiral bidentate ligand with broad applicability. Hoppe was the first to use a mixture of alkyllithium and (-)-sparteine (Figure 1) for very effective asymmetric deprotonations. [1] Beak examined enantioselective deprotonations of N-Boc-pyr­rolidines and N-Boc-allylamines. [2] Furthermore, it was used for dynamic resolutions [3] and deprotonations [4] of phosphine-boranes, for asymmetric additions of alkyllithiums to imines, [5] for asymmetric carbometallations of cinnamyl derivatives, [6] for palladium-catalyzed oxidative kinetic resolutions of secondary alcohols, [7] and for enantioselective syntheses of ferrocenes with planar chirality. [8]

The title compound is an alkaloid, which can be isolated from certain papilionaceous plants such as Scotch broom. [9] Its antipode is also naturally occurring but can be obtained far less easily. An 18 steps asymmetric total synthesis of (+)-sparteine starting from norbornadiene has been reported. [10] A (+)-sparteine surrogate is readily available from (-)-cytisine. [11]

(-)-Sparteine is commercially available as a free base or as the sulfate-pentahydrate. The chiral ligand can usually be recovered from the reaction mixtures by alkaline extraction.

Figure 1

References

• 1a Hoppe D. Zschage O. Angew.Chem. Int. Ed.  1989,  28:  69 
• 1b Hoppe D. Hintze F. Tebben P. Angew. Chem. Int. Ed.  1990,  29:  1422 
• 1c Hoppe D. In Encyclopedia of Reagents for Organic Synthesis   Vol. 7:  Paquette LA. Wiley; Chichester: 1995.  p.4662 
• 1d Hoppe D. Hense T. Angew. Chem. Int. Ed.  1997,  36:  2282 
• 1e Özlügedik M. Kristensen J. Wibbeling B. Fröhlich R. Hoppe D. Eur. J. Org. Chem.  2002,  414 
• 1f Hoppe D. In Topics in Organometallic Chemistry   Hodgson DM. Springer; Heidelberg: 2003.  Vol. 5. p.61 
• 2a Kerrick ST. Beak P. J. Am. Chem. Soc.  1991,  113:  9708 
• 2b Weisenburger GA. Beak P. J. Am. Chem. Soc.  1996,  118:  12218 
• 2c Beak P. Basu A. Gallagher DJ. Park YS. Thayumanavan S. Acc. Chem. Res.  1996,  29:  552 
• 2d Basu A. Thayumanavan S. Angew. Chem. Int. Ed.  2002,  41:  717 
• 3 Wolfe B. Livinghouse T. J. Am. Chem. Soc.  1998,  120:  5116 
• 4a Nagata K. Matsukawa S. Imamoto T. J. Org. Chem.  2000,  65:  4185 
• 4b Wolfe B. Livinghouse T. J. Org. Chem.  2001,  66:  1514 
• 5 Denmark SE. Nakajima N. Nicaise OJ.-C. J. Am. Chem. Soc.  1994,  116:  8797 
• 6a Klein S. Marek I. Poisson JF. Normant JF. J. Am. Chem. Soc.  1995,  117:  8853 
• 6b Norsikian S. Marek I. Klein S. Poisson JF. Normant JF. Chem.-Eur. J.  1999,  5:  2055 
• 7a Jensen DR. Pugsley JS. Sigman MS. J. Am. Chem. Soc.  2001,  123:  7475 
• 7b Ferreira EM. Stoltz BM. J. Am. Chem. Soc.  2001,  123:  7725 
• 8a Tsukazaki M. Tinkl M. Roglans A. Chapell BJ. Taylor NJ. Snieckus V. J. Am. Chem. Soc.  1996,  118:  685 
• 8b Metallinos C. Snieckus V. Org. Lett.  2002,  4:  1935 
• 9a Stenhouse J. Ann. Chem. Pharm.  1851,  78:  1 
• 9b Mills EJ. Ann. Chem. Pharm.  1863,  125:  71 
• 9c Boczo W. Heterocycles  1992,  33:  1101 
• 10 Smith BT. Wendt JA. Aubé J. Org. Lett.  2002,  4:  2577 
• 11 Dearden MJ. Firkin CR. Hermet J.-PR. O’Brien PJ. J. Am. Chem. Soc.  2002,  124:  11870 
• 12 Kise N. Urai T. Yoshida J. Tetrahedron: Asymmetry  1998,  9:  3125 
• 13a Bailey WF. Mealy MJ. J. Am. Chem. Soc.  2000,  122:  6787 
• 13b Sanz Gil G. Groth U. J. Am. Chem. Soc.  2000,  122:  6789 
• 14 Barluenga J. Fañanás FJ. Sanz R. Marcos C. Org. Lett.  2002,  4:  2225 
• 15 MacMillan JB. Molinski TF. Org. Lett.  2002,  4:  1883 
• 16 Shintani R. Fu GC. Angew. Chem. Int. Ed.  2002,  41:  1057 
• 17a Hodgson DM. Lee GP. Marriott RE. Thompson AJ. Wisedale R. Witherington J. J. Chem. Soc., Perkin Trans. 1  1998,  2151 
• 17b Hodgson DM. Maxwell CR. Miles TJ. Paruch E. Stent MAH. Matthews IR. Wilson FX. Witherington J. Angew. Chem. Int. Ed.  2002,  41:  4313