Until recently, sparteine, a widely used ligand in asymmetric synthesis1-5 was only commercially available in one enantiomeric form. O'Brien and his coworkers have designed several (+)-sparteine surrogates, which possess most of the threedimensional architecture of (+)-sparteine. However the N-methyl derivative (690279) shown in Figure 1 turned out to be the most versatile and widely applicable one.6
A simple, three-step synthesis starting from Laburnum anagyroides cytisus seeds, subsequent N-protection, diastereoselective pyridone hydrogenation, and lithium aluminum hydride reduction synthesized (Scheme 1).7
In a diverse range of examples was shown that all of the products show opposite enantioselectivity and a relatively equal high degree of enantioselection when using the (+)-sparteine surrogate (690279) to those when using (-)-sparteine.6,7
Lithiations and subsequent rearrangement or electrophilic trapping are particularly successful (Entries 1–4). The use of (+)-sparteine surrogate 690279 is not limited to organolithium-mediated processed reactions, magnesium, copper, and palladium are also successful. Exceptional examples include sparteine-mediated Grignard reactions in the desymmetrization of meso-anhydrides (Entry 5), and the copper(II)-mediated dynamic thermodynamic resolution of racemic BINOL (Entry 6).
We are pleased to now offer (+)-sparteine surrogate (690279) thus allowing access to a range of products of opposite absolute configuration to those obtained by using (-)-sparteine.