1,2-Redox Transpositions of Tertiary Amides

Reactions capable of transposing the oxidation levels of adjacent carbon atoms enable rapid and fundamental alteration of a molecule's reactivity. Herein, we report the 1,2-transposition of the carbon atom oxidation level in cyclic and acyclic tertiary amides, resulting in the one-pot synthesis of 1,2- and 1,3-oxygenated tertiary amines. This oxidation level transfer was facilitated by the careful orchestration of an iridium-catalyzed reduction with the functionalization of transiently formed enamine intermediates. A novel 1,2-carbonyl transposition is described, and the breadth of this redox transposition strategy has been further explored by the development of aminoalcohol and enaminone syntheses. The diverse β-functionalized amine products were shown to be multifaceted and valuable synthetic intermediates, accessing challenging biologically relevant motifs.

Cyclization/hydrolysis of 1,5-enenitriles initiated by sulfonyl radicals in the aqueous phase in the presence of the I2/TBHP system

A novel cyclization/hydrolysis of 1,5-enenitriles for the synthesis of valuable pyrrolidine-2,4-diones in the aqueous phase using I₂ as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant is reported. In the presence of the I₂/TBHP system, sulfonyl hydrazides produce sulfonyl radicals, which undergo radical addition, intramolecular cyclization, hydrogen abstraction, and hydrolysis to give the final products. The use of the inexpensive and environmentally friendly I₂/TBHP catalytic oxidation system in the aqueous phase makes it a benign and sustainable strategy.

Accessing oxy-functionalized N-heterocycles through rose bengal and TBHP integrated photoredox C(sp3)–O cross-coupling

A C(sp3)–O coupling strategy is described involving tautomerizable N-heterocycles (phthalazinone, pyridne, pyrimidinone and quinoxalinone) carbonyl employing rose bengal as the photocatalyst and TBHP.

Synthesis of 3,3′-bisindoles via demethylenation

This work provides a mild demethylenation for the synthesis of 3,3′-bisindoles.

Rapid and Mild Lactamization Using Highly Electrophilic Triphosgene in a Microflow Reactor

Lactams are cyclic amides that are indispensable as drugs and as drug candidates. Conventional lactamization includes acid-mediated and coupling-agent-mediated approaches that suffer from narrow substrate scope, much waste, and/or high cost. Inexpensive, less-wasteful approaches mediated by highly electrophilic reagents are attractive, but there is an imminent risk of side reactions. Herein, a methods using highly electrophilic triphosgene in a microflow reactor that accomplishes rapid (0.5-10 s), mild, inexpensive, and less-wasteful lactamization are described. Methods A and B, which use N-methylmorpholine and N-methylimidazole, respectively, were developed. Various lactams and a cyclic peptide containing acid- and/or heat-labile functional groups were synthesized in good to high yields without the need for tedious purification. Undesired reactions were successfully suppressed, and the risk of handling triphosgene was minimized by the use of microflow technology.

Selective cleavage and reconstruction of C–N/C–C bonds in saturated cyclic amines: tunable synthesis of lactams and functionalized acyclic amines

Selective cleavage of C–N/C–C bonds in saturated cyclic amines for the tunable synthesis of lactams and functionalized acyclic amines under the promotion of oxoammonium salt and TBHP in the presence of different additives have been developed.

Meirelis F, Vieira BGN. Divergent and Diastereoselective Synthesis of α-Monosubstituted and trans-α,β-Disubstituted γ-Lactams from (S)-N,N-Dibenzyl-α-amino Aldehydes via Henry and Michael Reactions

γ-Monosubstituted and trans-α,β-disubstituted γ-lactams were diastereoselectively synthesized from common intermediates (S)-N,N-dibenzylated aldehydes derived from natural l-(α)-amino acids, employing a divergent approach. The key features of the routes include diastereoselective Henry and Michael reactions that produced chiral γ-nitroester derivatives, which were subsequently submitted to a tandem reduction-lactamization sequence providing the title compounds. The versatility of routes can allow the preparation of several other mono-, di-, or tri-substituted γ-lactams.