Selective cleavage of the N-propargyl group from sulfonamides and amides under ruthenium catalysis

Photomediated Spirocyclization of N-Benzyl Propiolamide with N-Iodosuccinimide for Access to Azaspiro[4.5]deca-6,9-diene-3,8-dione

A metal- and oxidant-free route for affording azaspiro[4.5]deca-6,9-diene-3,8-dione via photomediated iodinated spirocyclization of N-(4-methoxybenzyl) propiolamide has been developed. The reaction underwent a radical addition/ipso-cyclization/dearomatization process at room temperature and successfully constructed C-C and C-I bonds. This green and convenient approach could be generally expanded to produce a range of iodinated spirocyclization products in moderate to good yields.

Formation of the Tertiary Sulfonamide C(sp3)-N Bond Using Alkyl Boronic Ester via Intramolecular and Intermolecular Copper-Catalyzed Oxidative Cross-Coupling

A synthetic strategy for the formation of C(sp³)-N bonds, particularly through a copper-catalyzed oxidative cross-coupling, is rare. Herein, we report a novel synthetic approach for the preparation of tertiary sulfonamides via copper-catalyzed intra- and intermolecular oxidative C(sp³)-N cross-coupling reactions. This method allows the utilization of the readily available C(sp³)-based pinacol boronate as a substrate and the tolerance of a wide range of functional groups under mild reaction conditions. The success of this strategy relies on the unprecedented additive effects of silanol and NaIO₄.

Highly Selective and Catalytic C-N Bond Cleavage of Tertiary Sulfonamides: Scope and Mechanistic Insight

A highly chemoselective C-N bond cleavage reaction of p-methoxybenzyl- (PMB), 3,4-dimethoxybenzyl- (DMB), or cinnamyl-substituted tertiary sulfonamides in the presence of catalytic Bi(OTf)₃ is presented. A wide range of sulfonamide substrates smoothly furnished the corresponding C-N bond cleavage products in good to excellent yields. Great efforts have been made to obtain insights into the reaction mechanism based on a series of control experiments and mass spectroscopy.

Regio- and Stereoselective (SN2) N-, O-, C- and S-Alkylation Using Trialkyl Phosphates

Bimolecular nucleophilic substitution (SN2) is one of the most well-known fundamental reactions in organic chemistry to generate new molecules from two molecules. In principle, a nucleophile attacks from the back side of an alkylating agent having a suitable leaving group, most commonly a halide. However, alkyl halides are expensive, very harmful, toxic and not so stable, which makes them problematic for laboratory use. In contrast, trialkyl phosphates are inexpensive, readily accessible and stable at room temperature, under air, and are easy to handle, but rarely used as alkylating agents in organic synthesis. Here, we describe a mild, straightforward and powerful method for nucleophilic alkylation of various N-, O-, C- and S-nucleophiles using readily available trialkyl phosphates. The reaction proceeds smoothly in excellent yield, and quantitative yield in many cases, and covers a wide range of substrates. Further, the rare stereoselective transfer of secondary alkyl groups has been achieved with inversion of configuration of chiral centers (up to 98% ee).

Synthesis of protected α-amino acids via decarboxylation amination from malonate derivatives

A general and efficient strategy for the synthesis of protected α-amino acids is reported. The method uses malonate derivatives as the starting materials and Cs2CO3 as a base at 60 degrees, giving α-amino acid derivatives in moderate yields by releasing CO2. This methodology shows broad substrate scope (primary and secondary acids), excellent functional group tolerance and high efficiency to give the desired products under mild reaction conditions. It also allows the construction of β and γ-amino acids and other unnatural products.