Camphorsultam absolute configuration

Fluorination of Ester Enolates. (+)-N-Fluoro-2,10-(3,3-dichlorocamphorsultam) (1) also reacts with the enolates generated from esters. For example, treatment of methyl 2-phenylpropionate 6 with NaHMDS in THF followed by addition of (+)-l affords the corresponding a-fluoro ester 7 in 54% yield and 33% ee (eq 3). The absolute configuration was not determined. The enantioselectivity observed with (+)-l is better than (—)-N-fluoro-2,10-camphorsultam i.e., < 10% ee (30% yield). ... 

Palladium-catalyzed cyclopropanation using diazomethane has been achieved stereoselectively on a series of a,)9-unsaturated carboxylic acids derivatized with camphorsultam as a chiral auxiliary. The selectivity of the reaction produces cyclopropanated products 22 with the absolute configuration. The stereoselectivity of the reactions is temperature dependent. Several A-enoylsultams 21 were successfully cyclopropanated in this manner. It was found that branching at the a- or /i-carbons disfavors complete conversion an electron-withdrawing substituent at the )9-position is particularly unfavorable. The chiral auxiliary was removed by using titanium(IV) isopropoxide in benzyl alcohol followed by alkaline hydrolysis of the intermediate ester providing cyclopropanated derivatives 23b of high diastereomeric purity. ... 

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