Ah ighly enantioselective synthesis of 1,4-enynes is described that proceeds through an organocatalytic reaction between propargyl alcohols and trialkenylboroxines.O ur strategy relies on acid-mediated generation of the carbocationic intermediate from propargyl alcohols followed by enantioselective alkenylation with trialkenylboroxines.Arange of chiral 1,4-enynes were obtained in moderate to good yields with high levels of enantioselectivity.U se of ah ighly acidic chiral Ntriflyl phosphoramide catalyst, which has two distant Lewis basic oxygen atoms,w as found to be crucial for both high reactivity and selectivity in the present reaction. Scheme 1. Transition metal-catalyzed asymmetric synthesis of 1,4enynes.Scheme 2. Synthesis of 1,4-enynes by alkenylation of propargyl alcohols.

An efficient synthesis of α-alkynylor α-allyl-substituted N-Boc-propargylic amines is described via an alkynylation or allylation of alkynyl-substituted N-Boc-imines. Our strategy relies on the BF 3 -mediated in situ generation of alkynyl imines followed by alkynylation or allylation with the corresponding boronic esters. A range of less accessible N-Bocpropargylic amines were obtained in moderate to good yields under mild and acidic conditions with higher atom economy compared to the previous methods.

An acid-catalyzed aza-Prins-type endo cyclization of 2-alkenylbenzaldehydes with BocNH or aniline derivatives through in situ generation of iminium intermediates has been developed, and various 1-aminoindene derivatives were readily obtained. The first catalytic asymmetric variant of the present reaction has also been demonstrated.

Cyclic carbamates were synthesized by the acid‐catalyzed reaction between Boc‐protected aminals as an imine precursor and 4‐methoxyphenyl‐substituted alkynes. The resulting cyclic carbamates could be converted to the one carbon ring‐contracted cyclic carbamates by ozonolysis. Consequently, 4‐methoxyphenyl‐substituted alkynes served as masked acyl anion equivalents.

The axially chiral biphenols are known as a broadly applicable chiral source. However, only a few electron-deficient ones have been reported to date. In the present study, chiral biphenols having several electron-withdrawing groups have been designed, and a facile synthetic route from readily available reagents has been developed. Newly synthesized chiral electron-deficient biphenols and biphenol-derived chiral Brønsted acids functioned as effective catalysts for several catalytic asymmetric reactions.

A highly enantioselective synthesis of 1,4‐enynes is described that proceeds through an organocatalytic reaction between propargyl alcohols and trialkenylboroxines. Our strategy relies on acid‐mediated generation of the carbocationic intermediate from propargyl alcohols followed by enantioselective alkenylation with trialkenylboroxines. A range of chiral 1,4‐enynes were obtained in moderate to good yields with high levels of enantioselectivity. Use of a highly acidic chiral N‐triflyl phosphoramide catalyst, which has two distant Lewis basic oxygen atoms, was found to be crucial for both high reactivity and selectivity in the present reaction.

The Cu-catalyzed asymmetric conjugate addition of trialkenylboroxines to enone diesters is reported. This operationally simple and scalable reaction proceeded at room temperature, and a wide range of enone diesters and boroxines were tolerated under the applied reaction conditions. The practical utility of this approach was demonstrated via the formal synthesis of (+)-methylenolactocin. Mechanistic studies revealed that two different catalytic species work synergistically in the reaction.