Mild reaction conditions are the advantage of the title reaction, which allows straightforward entry to a variety of ynamides starting from readily available 1,1-dibromo-1-alkenes, which act as attractive alkynylating agents (see scheme; EWG = electron-withdrawing group, DMF = N,N-dimethylformamide).
This review article presents how nitrogen-centred Lewis bases were modified in order to increase their reactivity in catalytic processes. As examples, we focus on alcohol acylation and Morita-Baylis-Hilman reactions in order to showcase the fundamental parameters at play in transformations initiated by catalysts bearing respectively an active sp(2) or sp(3) nitrogen atoms. These two aspects are epitomised by two leading compounds, the Steglich base 4-dimethylaminopyridine (DMAP), and 1,4-diazabicyclo[2.2.2]octane (DABCO). Throughout this review, we stress the role played and the information brought by physical organic chemistry. Comprehension of these complex transformations relies on the fundamental knowledge of parameters, such as, nucleophilicity, nucleofugality, Lewis basicity, and crucially also the knowledge of their divergent impacts on each elementary step of the catalytic cycle.
A couple of coppers: An efficient, asymmetric synthesis of the sedative cyclopeptide alkaloid paliurine F has been achieved. The strategy employs two copper(I)‐mediated coupling reactions as key steps to install the aryl ether linkage as well as to form the enamide with a concomitant unprecedented macrocyclization.
This microreview presents the use of 1,3-oxazolidines, prepared from enantiomerically pure β-amino alcohols, as chiral inductors for the stereoselective transformation of adjacent prostereogenic C=C or C=O bonds. After a brief chronological presentation of the major advances in this field, a convenient synthesis of N-Boc-2-acyl-and -2-alkenyloxazolidines is presented, together with the use of these heterocycles in asymmetric synthesis. The important role played by the Boc group on the nitrogen of the heterocycle in these trans-
An efficient copper-mediated method for the oxidative alkynylation of diaryl imines with terminal alkynes is reported. This reaction provides the first catalytic and general synthesis of ynimines and allows for an easy preparation of these useful building blocks. An improved copper-catalyzed oxidative dimerization of imines to azines and the synthesis of dienes and azadienes from ynimines are also described.
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