Diastereoselective Base-Catalyzed Formal [4 + 2] Cycloadditions of N-Sulfonyl Imines and Cyclic Anhydrides

Abstract

A diastereoselective base-catalyzed Mannich reaction of cyclic, enolizable anhydrides and N-sulfonyl imines for the synthesis of δ-lactams is reported. This anhydride Mannich reaction tolerates imines derived from aryl and enolizable aldehydes. A base-catalyzed product epimerization pathway ensures high anti diastereoselectivity in aryl and achiral enolizable imines.

Acyclic Stereocontrol in the Additions of Nucleophilic Alkenes to α‐Chiral N‐Sulfonyl Imines

“…Walsh has reported remarkable syn-selectivity in the addition of organozinc reagents [20,21] to a-chloro N-sulfonyl imines, and as ingle occurrence [21] of an anti-addition using alkynyllithium. [23] We had difficultyr ationalizing the syn,o rC ram-predicted, major products because little had been reported on analogous additions using soft nucleophilesi nt he absence of chelatable metals. [22] With these few examples as ab ackdrop, there has been no systematic study of a-alkoxyi mines that would provide similar insightt ot heir extensively-studied carbonyl counterparts.…”

“…Our interesti nt hese additions was sparkedd uring an investigation into the Brønsted base-mediated formation of d-lactams from a-chiral N-sulfonyl imines and anhydride enolates. [23] We had difficultyr ationalizing the syn,o rC ram-predicted, major products because little had been reported on analogous additions using soft nucleophilesi nt he absence of chelatable metals. We set out to develop conditions that would enablec omplete stereocontrol in the formation of an ew stereogenic center from a-chiral N-sulfonyl imines and soft nucleophiles alongside as tereoelectronic model that is consistentw ith our reaction outcomes and provides predictive power.…”

“…With these few examples as a backdrop, there has been no systematic study of α‐alkoxy imines that would provide similar insight to their extensively‐studied carbonyl counterparts. Our interest in these additions was sparked during an investigation into the Brønsted base‐mediated formation of δ‐lactams from α‐chiral N ‐sulfonyl imines and anhydride enolates . We had difficulty rationalizing the syn , or Cram‐predicted, major products because little had been reported on analogous additions using soft nucleophiles in the absence of chelatable metals.…”

Recent Advances in Synthesis of 3,4‐Dihydroisoquinolin‐1(2H)‐one

“…A base catalyzed Mannich type of the reaction of enolizable cyclic anhydride 130 with the N-sulfonylimine (135) gives the access to the 3,4-dihydroisoquinolin-1(2H)-one (136) up to 95% yield and anti diastereoselectivity up to 95 : 5 (Scheme 55). [74] M. Krasavin et al constructed 3,4-dihydroisoquinolin-1(2H)one (138) by using Castagnoli-Cushman reaction of homophthalic anhydride 130 with aldazine (137). The reaction proceeds smoothly at room temperature and yields predominately kinetic cis product which converted to its trans isomer by heating in DMSO or by treatment with base imidazole (Scheme 56).…”

Synthesis of Nitroaromatic Compounds via Three-Component Ring Transformations

“…There are four types of ring transformations, namely, Diels–Alder-type, decarboxylative, degenerate, and nucleophilic-type ring transformations ( Scheme 2 ). The most commonly used methods are Diels–Alder-type ring transformation (type a) [ 1 , 2 , 3 ] and decarboxylative ring transformation (type b) [ 4 , 5 , 6 ], wherein the substrates have a good leaving group as a partial structure (molecular nitrogen and carbon dioxide, respectively). Degenerated ring transformation was energetically studied by van der Plas [ 7 ].…”