Mechanistic insights into the gold(i)-catalyzed annulation of propiolates with isoxazoles: a DFT study

Abstract

The detailed mechanisms of gold(i)-catalyzed annulations of propiolates with substituted and unsubstituted isoxazoles were investigated by DFT calculations.

Theoretical evaluation of the carbene-based site-selectivity in gold(iii)-catalyzed annulations of alkynes with anthranils

“…Then the 2M N atom, acting as a nucleophile, attacks the alkyne internal C atom of IM1 due to the greater electron-deficiency of the Please do not adjust margins Please do not adjust margins internal C over the terminal C, as indicated by the calculated NBO charges (0.385e for the former and -0.443e for the latter). Through TS2-3, the necessary Au(III) carbenoid IM3 can then be formed by cleaving the N-O bond 7,8 with a barrier of 10.9 kcal mol -1 . From IM3, C a nucleophilic attack at carbene C will exclusively produce product P a .…”

Computational insight into gold(i)-catalyzed intramolecular regioselectivity of tryptamine-ynamide cycloisomerizations

“…49,55 The reason behind similar substrates following different cycloisomerization pathways is yet to be understood despite various experimental 49,57 and theoretical studies. [60][61][62][63][64][65] To probe into the origin of the gold(I)-catalyzed intramolecular regioselectivity of tryptamine-ynamide cycloisomerizations, systematic computational studies using density functional theory (DFT) calculations were carried out in the four studies mentioned above to gain insight into the substrate-dependent mechanisms of these transformations. Our results showed that the non-covalent interactions between the terminal substituent of the alkynyl and the gold(I) catalytic ligand determined the regioselectivity of the reaction pathway.…”

Theoretical Insights into Ester-Directed Reactions between Propiolates with 1,2-Benzisoxazoles by Au(I) Catalyst: [4 + 2]-Annulation versus Michael-Type Products

“…Gold-catalyzed annulations of alkynes with N–O-containing nucleophiles represent efficient and powerful strategies to selectively access versatile carbon- and azaheterocycles . With electron-rich ynamides, gold-catalyzed annulations focus intensely on diverse nitroxy heterocyclic nucleophiles, including isoxazole derivatives, , 1,2,4-oxadiazoles, 4,5-dihydro-1,2,4-oxadiazoles, and 1,4,2-dioxazoles . In addition, electron-deficient propiolates are recently developed as suitable substrates, participating into a series of gold-catalyzed formal annulations of nitroxy heterocycles, among which, 1,2-benzisoxazoles and anthranils are two structurally analogous N,O-functionalized reagents.…”