Xiyan Lu

TL;DR: This study illuminates the unusual phenomena and shows how understanding of the central problem to generate a 1,3-dipole from alkynoates or allenoates by interaction with various phosphines allows control of the reaction.

Abstract: The reactivity of a new three carbon synthon, generated in situ from the reaction of 2,3-butadienoates or 2-butynoates with an appropriate phosphine as the catalyst, toward the electron-deficient imines is described. Triphenylphosphine-catalyzed reaction of methyl 2,3-butadienoate with N-sulfonylimines gave the single [3+2] cycloadduct in excellent yield; tributylphosphine-catalyzed reaction of methyl 2,3-butadienoate or 2-butynoate with N-tosylimines afforded the corresponding [3+2] cycloadduct as the major product along with a small amount of the three components adduct. Aliphatic N-tosylimines gave moderate yield for this reaction. In addition, a new phosphine-catalyzed cyclization reaction of dimethyl acetylenedicarboxylate with N-tosylimines is also described. A reaction mechanism is proposed. Further elaborations of the cycloaddition products and the synthesis of pentabromopseudilin using this method are exemplified.

TL;DR: A novel oxidizing directing group was developed for a rhodium(III)-catalyzed CH functionalization of N-phenoxyacetamides with alkynes to deliver benzofurans with high selectivity.

TL;DR: In the presence of a catalytic amount of triphenylphosphine, methyl 2,3-butadienoate smoothly reacted with aromatic or heteroaromatic N -tosylimines at room temperature to afford the [3+2] cycloaddition product in excellent yield as mentioned in this paper.