Solvent‐Free, Metal‐Free, Aza‐Prins Cyclization: Unprecedented Access to δ‐Sultams

Abstract

Aza-Prins and the pauper: Aza-Prins cyclization between γ,δ-unsaturated tosylamines and aldehydes was successfully performed under solvent-free and metal-free conditions. When applied to β,γ-unsaturated sulfonamides, the corresponding δ-sultams were isolated in good yields (see scheme). This approach constitutes a new route to cyclic sulfonamides.

Sequential Oxidation-Prins Reaction Processes Induced by the Same Iron Salt: Direct Access to 2-Aryl-4-Chloro-Tetrahydropyrans from Benzyl ­Alcohols

“…19 To our delight, 2-phenyl-4-chloro piperidine was isolated in 60% overall yield as a 9:1 mixture of trans/cis isomers. This value could be advantageously compared to those obtained by Padron et al 31 using stoichiometric FeCl 3 and starting from benzaldehyde.…”

Saturated Bicyclic Sultams

“…Surprisingly, none of the methods disclosed for spirocyclic β‐ and γ‐sultams were applied for the preparation of saturated δ‐counterparts. One of the approaches used instead included the intermolecular aza‐Prins reaction of allyl sulfonamide 150 and cycloalkanones, which provided β‐iodosultams 151 in moderate yields (48–58 %) (Scheme ) …”

Synthesis of 3-Iodomethyl Sultams

“…For example, the oxidation of homocystine gave sultams bearing a carboxyl group 22 and aza-Prins reaction of N-substituted sulfamides led to substituted halosultams. 23 The catalytic haloamination reaction is an effective method for a C-N bond formation. It enables the regio-and stereoselective vicinal difunctionalization of alkenes with amine and halogen moieties.…”