PhD student, Jinjin Ma, presents Exploiting Cyanohydrin-Derived Carbanions for Stereochemical Control in Organic Synthesis

Exploiting Cyanohydrin-Derived Carbanions for
Stereochemical Control in Organic Synthesis

Jinjin Ma |  Evans Group, Queen’s University  |  October 9, 2026

ABSTRACT

Cyanohydrins serve as acyl anion equivalents for carbon–carbon bond formation through carbonyl umpolung.  This seminar explores complementary strategies that harness their reactivity to control alkene geometry and construct enantioenriched α-tertiary ketones.  The first part presents two approaches to Z-tetrasubstituted alkenes.  Diastereomeric resolution exploits selective deprotonation and electrophilic trapping of the E-isomer, allowing recovery of the enriched Z-isomer.  Dynamic thermodynamic resolution instead exploits allylic carbanion equilibration to favour the Z-isomer upon protonation, with application to the total synthesis of murralonginal.  The second part describes transition-metal-free enantiospecific alkylation of cyanohydrins with enantioenriched secondary tosylates, affording α-tertiary ketones after carbonyl unmasking.  With alkenyl cyanohydrins, coupling alkylation with olefin dynamic kinetic resolution controls both alkene geometry and carbon stereochemistry.  An enantiospecific synthesis of (R)-cyclamen aldehyde illustrates the method’s synthetic utility.  Overall, these studies establish cyanohydrin-derived nucleophiles as a platform for complementary control of geometric and configurational stereochemistry.