Syntheses of Nitrogen Containing Compounds Using Reactive Organometallics

Diastereoselective carbon-carbon bond formation is accomplished using activated imines with organocuprates-BF₃·OEt₂ complexes or allylic organometallic compounds such as allyl-9-BBN and allyltributylstannane-TiCl₄. Very high 1, 2- and 1, 3-asymmetric induction is achieved in the reaction of allyl-9-BBN, allylmagnesium chloride and allylaluminum ate complexes with certain chiral imines. Iminium ion intermediates generated from α-alkoxycarbamates are detected by NMR at low temperatures. Significantly high diastereoselectivities are observed in the reactions of iminium ions with organoleads, allylic stannanes and organocuprate-BF₃ reagents. It is proposed that ZnCl₂·OEt₂ works as a radical initiator as well as a chelating agent in the reaction of the ZnCl₂ mediated allylation of α-bromoglycine derivatives with allylic stannanes. Transition metal catalyzed C-C bond formation takes place successively in the reaction of activated imines with activated nucleophiles such as malononitrile and α-alkoxy malononitrile. Lithium N -benzyltrimethylsilylamide (LSA) regioselectively adds to α, β-unsaturated esters in a 1, 4-manner. Higher order cyano cuprate type analogues of LSA react regioseletively with α, β, γ, δ-unsaturated esters in a 1, 4-manner to give the corresponding β-amino esters. This cuprate amide reagent is applied to the highly stereoselective synthesis of β-lactam frameworks. Asymmetric carbocyclization is achieved via the tandem conjugate addition of metal amides to certain dienoates.