Highly Enantioselective Desymmetrization of Anhydrides by Carbon Nucleophiles: Reactions of Grignard Reagents in the Presence of (−)-Sparteine

Abstract

Where other common chiral ligands failed, (−)‐sparteine can be employed to form complexes with Grignard reagents. These chirally modified reagents desymmetrize a range of anhydrides with good enantioselectivity (up to 92 % ee; see scheme). Whereas (−)‐sparteine is well known to form complexes with organolithium reagents and to induce excellent enantioselection in their reactions with electrophiles, (−)‐sparteine‐controlled asymmetric processes that involve Grignard reagents are rare.

First asymmetric synthesis of a C2-symmetric 2-endo,6-endo-disubstituted bispidine

“…7 It has also successfully been applied in enantioselective allylic substitutions, 8 additions to imines 9 and the ring opening of meso-anhydrides. 10 Recent developments disclose the use of (À)-1 as a ligand in Cu I -mediated dynamic kinetic resolutions of racemic 1,1 0 -biaryl-2,2 0 -diols 11 and in Pd II -catalysed oxidative kinetic resolutions of secondary alcohols. 12 The lack of an easily accessible source for (+)-sparteine (+)-1 13 is compensated by the synthetic diamine (+)-2, 14,15 which is devoid of the axially annelated ring of 1, but offers a comparably high potential in asymmetric synthesis as (À)-1 does.…”

Design, synthesis and in vitro splicing inhibition of desmethyl and carba-derivatives of herboxidiene

“…The depicted stereochemistry was assigned based upon comparison of optical rotation of related compounds. 36,37 Diazo compound 20 was synthesized according to the procedure of Nicolaou and co-workers. 38,39 Carboxylic acid 19 was smoothly converted to diazo compound 20 by activation with CH 3 SO 2 Cl in the presence of Et 3 N at 0 °C followed by reaction of the resulting mesylate with diazomethane in ether at 0 °C for 30 min.…”

Enantioselective 1,3‐dipolar cycloaddition reactions using complexes of (−)‐sparteine

“…Initially organolithium compounds were applied in asymmetric deprotonation, substitution and addition reactions [21,22]. Later chiral complexes of sparteine with other metal ions were used, such as complexes of magnesium [23], tin [24], titanium [25,26], copper [27,28], manganese [29], and palladium [30,31].…”