Kinetic Resolution of Racemic 2,3-Allenoates by Organocatalytic Asymmetric 1,3-Dipolar Cycloaddition

Abstract

The kinetic resolution of racemic 2,3-allenoates was realized via 1,3-dipolar cycloaddition by using a bisphosphoric acid catalyst, affording the optically active 2,3-allenoates and 3-methylenepyrrolidine derivatives in high yields and enantioselectivities.

4.22 Intermolecular 1,3-Dipolar Cycloadditions of Alkenes, Alkynes, and Allenes

“…72 By using the same catalyst, they have also realized the kinetic resolution of racemic 2,3-allenoates 124 via the same reaction, affording the optically active 2,3-allenoates (R)-124 and 3-methylenepyrrolidine derivatives 125 in high yield and enantioselectivities (Scheme 60). 73 Recently, Wang and coworkers have demonstrated a catalytic asymmetric 1,3-dipolar cycloaddition of various azomethine ylides with diethyl 2-(3,3-diphenylpropa-1,2-dienylidene)malonate 126, aiming for an efficient construction of 3-vinylidenepyrrolidine derivatives 127 bearing an allene moiety (Scheme 61). 74 The reaction was promoted by an Ag(I)/TF-BiphamPhos 88 complex as catalyst.…”

Direct Synthesis of Chiral Allenoates from the Asymmetric CH Insertion of α‐Diazoesters into Terminal Alkynes

“…values by HPLC, 1l was selected as the representative 1-alkyne (Table 3). [15] Moreover, when 2-diazo-2-phenylacetate esters were employed (condi-tions B), there was no significant difference in enantioselectivity upon increasing the steric hindrance of the ester group (entries [9][10][11][12]. The a-alkyl-diazoesters 2f-h with longer aliphatic chains underwent the reaction in moderate yield and 93:7-94:6 e.r.…”

Enantioselective Synthesis of Multisubstituted Allenes by Cooperative Cu/Pd‐Catalyzed 1,4‐Arylboration of 1,3‐Enynes

“…[1] Allene chemistry has stimulated the interest of organic and medicinal chemists for decades.H owever,g eneral and efficient enantioselective synthetic method to access axially chiral allenes from prochiral precursors is al ongstanding challenge.M any classical methods predominantly rely on central-to-axial chirality transfer [2] or resolution of racemic allenes. [3] Until recently,i ncreasing attention has focused on developing catalytic asymmetric approaches for the synthesis of chiral allenes. [1f,h] Since the pioneering work of the group of Hayashi, [4] 1,3enynes have been gradually considered ideal achiral precursors for the construction of highly valuable chiral allenes,and several metal-or organocatalyzed approaches were established in the past few years.…”