Doug Schoon

Bio: Doug Schoon is an academic researcher. The author has contributed to research in topics: Cycloaddition. The author has an hindex of 1, co-authored 1 publications receiving 84 citations.

Cycloadditions of cyanoketenes to cinnamylidenamines and benzylidenamines. Synthetic scope, stereochemistry, and mechanism

Abstract: Cycloaddition de cyanocetenes (t-butylcyanocetene, chlorocyanocetene et hexynylcyanocetene) aux imines du titre. Influence de la taille et du degre d'insaturation des substituants de l'imine sur la stereo- et la periselectivite des cycloadditions

The mechanism of the ketene-imine (staudinger) reaction in its centennial: still an unsolved problem?

Abstract: Although Staudinger reported the reaction between ketenes and imines 100 years ago (1907), this process is still the most general and useful method for the synthesis of β-lactams and their derivatives. This reaction is a [2 + 2] thermal cycloaddition in which two chiral centers may be generated in one preparative step. Staudinger reactions involving α,β-unsaturated imines or ketenes have issues concerning the [2 + 2] or [4 + 2] periselectivity of the reaction. This Account discusses how the main factors that determine the regiochemical and stereochemical outcomes of this reaction were elucidated with computational and experimental data. This fruitful interplay between theory and experiment has revealed that the [2 + 2] cycloaddition is actually a two-step process. The first step is a nucleophilic addition of the nitrogen atom of the imine on the sp-hybridized carbon atom of the ketene. This attack forms a zwitterionic intermediate that evolves toward the final β-lactam cycloadduct. The second step can be ...

Acid-catalysed addition of N-aryl imines to dihydrofuran. Postulated dependence of the reaction mechanism on the relative face of approach of reactants

Abstract: Imines 1a and 1b react with dihydrofuran (DHF) under Lewis acid catalysis via Diels–Alder-type addition to form the tetrahydroquinoline derivatives 3a, b and 4a, b. Besides these compounds, the methanol adduct 2 of 1a, or 1a in the presence of methanol, gives the methanol-containing tetrahydrofuran derivative 7a and the hexahydrofuro[3,2-b]furan derivatives 5 and 6. In the presence of methanol, 1b gives 3b and 4b, and also 7b and 8. The products 3a, b, 5, 6 and 7a, b originate from approach of the Si(or Re) face of 1a, b onto the Si(or Re) face of DHF; 4a, b and 8 derive from interaction of the Si(or Re) face of 1a, b with the Re(or Si) face of DHF. The dependence of the product distribution on the polarity of the solvent suggests that a concerted mechanism predominates in the former mode and a zwitterionic one in the latter. In the addition of 1a or 2 the mechanistic preference may be exclusive.