Unmasking the reverse reactivity of cyclic N-sulfonyl ketimines: multifaceted applications in organic synthesis

Abstract

The chemistry related to the exploration of cyclic N-sulfonyl ketimines and their derivatives has attracted significant attention in the last few decades because of their intriguing structures and properties. They...

δ-Acetoxy Allenoate as a 5C-Synthon in Domino-Annulation with Sulfamidate Imines: Ready Access to Coumarins

“…In Lewis base-mediated/catalyzed annulations, δ-acetoxy allenoates can offer 5–8-membered ring scaffolds by the attack of the nucleophile at the δ- or α-carbon of an electrophilic intermediate, wherein the allenoate part offers 1C - 4C for the framework, but so far none of them utilized acetoxy allenoates as 5C- synthons (Scheme a–b) . Our interest in allene chemistry ,− , prompted us to explore annulations via the diene-ammonium intermediate, and in this context, we envisioned that annulation involving δ-acetoxy allenoate as 5C-synthon via the diene-ammonium intermediate is feasible with a suitable reaction partner such as sulfamidate-derived cyclic imines. , The latter imines have been explored in cyclization/annulation reactions in recent years, with the sulfamidate as a disposable entity in a couple of cases (Scheme c–d) …”

Palladium-catalysed enantio- and regioselective (3 + 2) cycloaddition reactions of sulfamidate imine-derived 1-azadienes towards spirocyclic cyclopentanes

“…2b). 57,58 Such (3 + 2) cycloadditions would proceed via a non-aromatic intermediate II, where attack by the nitrogen on the pendant p-allyl palladium complex would be unlikely as it would result in a strained bicyclic product. Furthermore, in contrast to BDA cycloaddition products, the oxygen substituent in the SDA-derived cyclopentanes would not be attached to an aromatic ring.…”

Organocatalytic Enantioselective Synthesis of Polycyclic Benzosultams from 2-Amino-β-nitrostyrenes with Cyclic N-Sulfonyl Ketimines

“…These processes result in the formation of a varied set of pharmacologically significant chiral cyclic sulfonamide and sulfamate scaffolds. 6 In our exploration of asymmetric cycloaddition with cyclic N-sulfonyl ketimines, our focus has been particularly directed toward [4 + 2] cycloaddition for the construction of polycyclic benzosultam. Despite the notable suitability of cyclic Nsulfonyl ketimines as substrates for benzosultam synthesis, there are relatively few reported examples showcasing their use in asymmetric [4 + 2] cycloadditions.…”