Base-Promoted Formal [3 + 2] Cycloaddition of α-Halohydroxamates with Carbon Disulfide to Synthesize Polysubstituted Rhodanines

Metal-Free One-Pot Domino Synthesis of Oxazolidinethione Derivatives of Quaternary Amino Acids from α-Amino Esters and Aldehydes Using CS2

We present a streamlined, metal-free, one-pot domino approach to efficiently synthesize oxazolidinethione derivatives containing substituted quaternary amino acids. This method employs α-amino esters, aldehydes, and CS2 under mild conditions, constructing three new bonds (C-N, C-C, and C-O) to produce oxazolidinethione compounds featuring a quaternary center and a beta-hydroxy derivative in high yields. This scalable protocol enables the creation of libraries of biologically significant, intricate amino acid derivatives using amino esters and aldehydes.

Base-Promoted Formal (3 + 2) Cycloaddition of α-Halohydroxamates with Electron-Deficient Alkenyl-iminoindolines To Synthesize Spiro-indolinepyrrolidinones

Construction of pyrrolidinyl-spiroindoles with easily available starting materials has attracted considerable attention from the synthesis community and is in great demand. Here, we describe a base-promoted formal (3 + 2) cycloaddition of α-halohydroxamates with alkenyl-iminoindolines. The present methodology features mild reaction conditions and a broad substrate scope with up to 99% yield and excellent diastereoselectivity. The versatility of this approach is demonstrated through valuable synthetic transformations. Preliminary mechanistic studies shed light on the mechanism of this cycloaddition process.

A concise approach to 2-pyrrolin-5-one scaffold construction from α-halohydroxamates and β-keto compounds

A concise approach to the construction of the 2-pyrrolin-5-one scaffold was developed via a one-pot reaction with formal [3 + 2] annulation/elimination between β-keto nitrile/β-keto ester and unsubstituted α-halohydroxamates. This reaction features mild conditions, easy handling, broad substrate scope and good yields. Remarkably, the products could be readily converted into potentially bioactive alkylidenepyrrolinones, pyrroles, pyran-fused pyrrole heterocycles and other useful compounds, exhibiting versatile synthetic potential.

Catalyst- and additive-free syntheses of rhodanine and S-alkyl dithiocarbamate derivatives from sulfoxonium ylides

An efficient catalyst- and additive-free facile access to rhodanine and S-alkyl dithiocarbamate derivatives via multi-component reaction of amines, CS₂ and α-ester sulfoxonium ylides in methanol has been described. The new synthetic methods offer excellent synthetic prospects for several functionalized rhodanines and S-alkyl dithiocarbamates with simple operational procedures.

Access to Sterically Hindered Thioethers (α-Thioamides) Under Mild Conditions Using α-Halohydroxamates: Application toward 1,4-Benzothiazinones and 4,1-Benzothiazepinones

Herein, we report a new and highly efficient approach for synthesizing congested α-thioamides under mild reaction conditions (mild base, room temperature, and short duration) using α-halo hydroxamates as direct alkylating agents. The reaction works well with both (hetero)aryl and alkyl thiols, tolerating a broad functional group and diverse substrate scope, including benzeneselenol for selenoether construction. The strategy enables efficient synthesis of biologically relevant 1,4 benzothiazinone and 4,1-benzothiazepinone cores, along with various other functionalized sulfur-based scaffolds of biological importance.

Access to 3,3'-disubstituted peroxyoxindole derivatives and α-peroxyamides via azaoxyallyl cation-guided addition of hydroperoxides

Herein, a transition metal-free approach for access to 3,3'-disubstituted peroxyoxindole is disclosed, which harnesses a transient azaoxyallyl cation. This strategy is also applicable to the synthesis of structurally diverse α-peroxycarboxylic acid surrogates. The method exhibits good functional group tolerance and is suitable for generating a library of peroxy-containing compounds.