Complementary Heterogeneous/Homogeneous Protocols for the Synthesis of Densely Functionalized Benzo[d]sultams: C−C Bond Formation by Intramolecular Nucleophilic Aromatic Fluorine Displacement

Immobilization of Trifluoromethyl-Substituted Pyridine-Oxazoline Ligand and Its Application in Asymmetric Continuous Flow Synthesis of Benzosultams

This study presents an improved synthetic route to ligand (S)-4-(tert-butyl)-2-(5-(trifluoromethyl)pyridin-2-yl)-4,5-dihydrooxazole and its application as a highly active and enantioselective catalyst in the addition of arylboronic acids to cyclic N-sulfonylketimines. Immobilization of such a ligand was achieved using a commercially available starting material and a PS-PEG TentaGel S NH2 support, resulting in a stable heterogeneous catalyst. Although the anchored catalyst exhibited a slight reduction in enantioselectivity and a 4-fold decrease in reaction rate, it displayed remarkable stability, enabling 10 consecutive reaction cycles. Furthermore, the successful transition to a continuous flow system demonstrated even higher turnover numbers compared to batch arrangements. These findings provide valuable insights into the development of efficient flow reactors for continuous synthesis of benzosultams, further advancing the field of asymmetric catalysis.

Modular Synthesis of α,α-Diaryl α-Amino Esters via Bi(V)-Mediated Arylation/SN2-Displacement of Kukhtin–Ramirez Intermediates

We report a concise and modular approach to α,α-diaryl α-amino esters from readily available α-keto esters. This mild, one-pot protocol proceeds via ketone umpolung, with in situ formation of a Kukhtin–Ramirez intermediate preceding sequential electrophilic arylation by Bi(V) and S_N2 displacement by an amine. The methodology is compatible with a wide range of anilines and primary amines - including derivatives of drugs and proteinogenic amino acids - Bi(V) arylating agents, and α-keto ester substrates.

Stereoselective synthesis of chiral sultam-fused dihydropyridinones via photopromoted NHC catalyzed [4 + 2] annulation

A photopromoted NHC catalyzed asymmetric [4+2] annulation of saccharine-derived azadienes and α-diazoketones was developed, affording the corresponding sultam-fused dihydropyridinones efficiently (up to 80% yield, 99% ee and >20 : 1 d.r.).

Unexpected distinction in reactivity of pentafluorobenzenesulfonyl halides toward organolithiums and organomagnesium halides

C6F5SO2Cl reacts with organolithiums and organomagnesium halides RM (R=Me, Bu, Ph; M=Li, MgX) to give mainly C6F5H and C6F5Cl. C6F5SO2Br and PhMgBr form C6F5H and (C6F5S)2. This is in contrast to known transformations of them which yield exclusively C6F5SO2Nu under the action of O- and N-nucleophiles. Alternatively, C6F5SO2F is converted to C6F5SO2R and 4-BuC6F4SO2F or 2-PhC6F4SO2Ph under the same conditions. When R=Me, minor amounts of (C6F5SO2)2CH2 and 4-C6F5SO2CH2C6F4SO2F form in addition to C6F5SO2CH3.

Rh(iii)-catalyzed tandem oxidative olefination-cyclization of aryl sulfonamides

An efficient Rh(iii)-catalyzed ortho-selective C–H activation and tandem oxidative olefination-cyclization of aryl sulfonamides is described. The protocol has been applied to various substrates with good functional group tolerance.

A formal [4 + 4] complementary ambiphile pairing reaction: a new cyclization pathway for ortho-quinone methides

A formal, one-pot [4 + 4] cyclization pathway for the generation of eight-membered sultams via in situ generation of an ortho-quinone methide (o-QM) is reported. The pairing of ambiphilic synthons in a complementary fashion is examined whereby o-fluorobenzenesulfonamides are merged with in situ generated o-QM in a formal [4 + 4] cyclization pathway to afford 5,2,1-dibenzooxathiazocine-2,2-dioxide scaffolds under microwave (mW) conditions. The method reported represents the first use of an o-QM in a formal hetero [4 + 4] cyclization.