hydrazone 1 ( 0.273 mmol ) , catalyst 7 ( 5 mol% ) , and mg(otbu)2 ( 5 mol% ) were combined in a 2 dram oven dried vial and capped with a teflon / silicon septum inside of a nitrogen drybox . the vial was removed from the drybox and thf ( 0.25 m ) was added and the vial was heated with moderate stirring in an aluminum heating block to 60 c for 1520 minutes . unsaturated aldehyde 2 ( 1.5 equiv ) and then tbd ( 10 mol % ) was immediately added . the reaction was allowed to continue at 60 c and was monitored by tlc ( 5% meoh / chcl3 ) upon completion ( 24 h ) , the reaction was diluted with ch2cl2 ( 15 ml ) and washed with a 1:1 mixture of saturated aqueous nh4cl and water ( 10 ml ) . the aqueous layer was back extracted ch2cl2 ( 2  15 ml ) and the combined organic layers were dried over anhydrous sodium sulfate and concentrated . the brown oily residue was purified by flash column chromatography on a biotage sp-1 chromatography system using a 12100% ethyl acetate / hexanes gradient to yield the desired product 3 .
enzymes are a continuing source of inspiration for the design of new chemical reactions that proceed with efficiency , high selectivity and minimal waste . in many biochemical processes , 
 different catalytic species , such as lewis acids and bases , are involved in precisely orchestrated interactions to activate reactants simultaneously or sequentially . employing this type of cooperative catalysis , in which two or more catalytic cycles operate concurrently to achieve one overall transformation , 
 has great potential to enhance known reactivity and drive the development of new chemical reactions with high value . in this disclosure , 
 a cooperative n - heterocyclic carbene / lewis acid catalytic system promotes the addition of homoenolate equivalents to hydrazones generating highly substituted -lactams in moderate to good yields and high levels of diastereo- and enantioselectivity .