Cyclopropanation chiral disulfonamide

Ukaji et al.117 reported an enantioselective cyclopropanation reaction in which moderate enantiomeric excess was obtained when a stoichiometric amount of diethyl tartrate was used as a chiral modifier. Takahashi et al.118 achieved better results using the C2-symmetric chiral disulfonamide 205 as the chiral ligand. 

There is only one example of a catalytic enantioselective cyclopropanation of allylic alcohols using an electron withdrawing chiral disulfonamide 19 as a chiral ligand (Protocol 6).33 Stoichiometric highly enantioselective cyclo-propanations of allylic alcohols are reported using a chiral diethyl tartrate34 and a chiral tartamide.35... 

Enantioselective cyclopropanation of an allylic alcohol using chiral disulfonamide (Structure 19) as a chiral catalyst336... 

Recently, many efforts have focused on the development of the enantioselective (iodomethyl)zinc-mediated cyclopropanation of allylic alcohols. Kobayashi and co-workers reported that moderate to good enantioselectivities were observed if a C2-symmetric chiral disulfonamide was added. To reduce the rate of uncatalyzed... 

Recently, many efforts have been focused on the development of the enantioselective (iodomethyl)zinc-mediated cyclopropanation of allylic alcohols. Kobayashi and co-workers reported that moderate to good enantioselectivities were observed if a Ci-symmetric chiral disulfonamide was added. " To reduce the rate of uncatalyzed process responsible for decrease of enantioselectivity, Charette and Brochu studied the effect of addition of Lewis acid, and proved that TiCU accelerates the reaction. The addition of the chiral titanium catalyst 548 allowed the conversion of 3-aryl and 3-heteroaryl-substituted allylic alcohols to the corresponding cyclopropane derivatives in enantiomeric ratios up to 97 3 (Scheme 2-154, eq. (a)). The dioxaborolane ligand 549 is an efficient chiral reagent for the enantioselective cyclopropanation not only of allylic alcohols but also of unconjugated and conjugated... 

---