PART I: PHOSPHINE-CATALYZED GAMMA-ADDITION: TOTAL SYNTHESIS OF ASPIDOSPERMA ALKALOIDS PART II: COPPER/PHOTOREDOX DUAL CATALYSIS: DECARBOXYLATIVE 1,4-CARBOCYANATION OF 1,3-ENYNES

Abstract

Part Ⅰ：Phosphine-catalyzed asymmetric γ-additions of carbazolones to allenoates to afford 3,3-disubstituted carbazolones have been established. Different substituted carbazolones could be employed in this process, catalyzed by a chiral phosphine derived from an amino acid, forming 3,3-disubstituted carbazolones in good yield and excellent enantioselectivity. This methodology was applied in the total synthesis of aspidosperma alkaloids. The critical synthetic features include a reductive-amination cyclization and nucleophilic substitution cyclization to install its carbocyclic skeleton efficiently.

Part Ⅱ: We disclose herein the first example of merging copper catalysis and photoredox catalysis for radical 1,4-carbocyanations of 1,3-enynes. Alkyl N-hydroxyphthalimide esters are utilized as radical precusors, and the reported mild and redox-neutral protocol has broad substrate scope and remarkable functional group tolerance. This strategy allows for the synthesis of diverse multi-substituted allenes with high chemo- and regio- selectivities, also permitting late stage allenylation of natural products and drug molecules.