2-Azaallyl Anion Initiated Ring-Opening Polymerization of N-Sulfonyl Aziridines: One-Pot Synthesis of Primary Amine-Ended Telechelic Polyaziridines

Organic Dye-Sensitized Nitrene Generation: Intermolecular Aziridination of Unactivated Alkenes

Aziridines are important structural motifs and intermediates, and several synthetic strategies for the direct aziridination of alkenes have been introduced. However, many of these strategies require an excess of activated alkene, suffer from competing side-reactions, have limited functional group tolerance, or involve precious transition metal-based catalysts. Herein, we demonstrate the direct aziridination of alkenes by combining sulfonyl azides as a triplet nitrene source with a catalytic amount of an organic dye functioning as photosensitizer. We show how the nature of the sulfonyl azide, in combination with the triplet-excited state energy of the photosensitizer, affects the aziridination yield and provide a mechanistic rationale to account for the observed dependence of the reaction yield on the nature of the organic dye and sulfonyl azide reagents. The optimized reaction conditions enable the aziridination of structurally diverse and complex alkenes, carrying various functional groups, with the alkene as the limiting reagent.

Tributylphosphine-catalyzed aziridine-based cycloaddition polymerization toward thiacyclic polymers

Cycloaddition polymerization of bis(N-sulfonyl aziridine)s with diisocyanates in the presence of tributylphosphine allows the facile synthesis of poly(thiazolidin-2-imine)s.

Synthesis of chiral β-substituted γ-amino-butyric acid derivatives via enantioconvergent ring opening of racemic 2-(hetero)aryl aziridines with ketene silyl acetals

Lewis acid-catalyzed enantioconvergent ring opening of racemic 2-(hetero)aryl-N-sulfonyl aziridines with ketene silyl acetals is developed.

Catalyst-free aziridine-based step-growth polymerization: a facile approach to optically active poly(sulfonamide amine)s and poly(sulfonamide dithiocarbamate)s

Step-growth polymerization of chiral bis(N-sulfonyl aziridine)s with diamines or bis(dialkyldithiocarbamate) in the absence of a catalyst allows the facile synthesis of optically active polysulfonamide derivatives.

Transition-metal-free allylation of 2-azaallyls with allyl ethers through polar and radical mechanisms

Allylation of nucleophiles with highly reactive electrophiles like allyl halides can be conducted without metal catalysts. Less reactive electrophiles, such as allyl esters and carbonates, usually require a transition metal catalyst to facilitate the allylation. Herein, we report a unique transition-metal-free allylation strategy with allyl ether electrophiles. Reaction of a host of allyl ethers with 2-azaallyl anions delivers valuable homoallylic amine derivatives (up to 92%), which are significant in the pharmaceutical industry. Interestingly, no deprotonative isomerization or cyclization of the products were observed. The potential synthetic utility and ease of operation is demonstrated by a gram scale telescoped preparation of a homoallylic amine. In addition, mechanistic studies provide insight into these C(sp3)-C(sp3) bond-forming reactions.

Grafting polysulfonamide from cellulose paper through organocatalytic ring-opening polymerization of N-sulfonyl aziridines

A facile and effective "grafting from" method by ROP of N-sulfonyl aziridines toward cellulose-g-polysulfonamides has been developed for efficient oil/water separation. The cellulose paper was initially succinylated to transform the hydroxyl to carboxyl acid groups, which act as the initiating sites for the ring-opening copolymerization of fluorescent 2-methyl-1-dansylaziridine and 2-methyl-1-tosylaziridine (TsMAz) towards the grafted cellulose. Both steps are catalyzed by the same compound, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The grafted polysulfonamide ratio was up to 136 wt%, and the surface contact angle up to 147°. A one-pot tandem strategy was applied to produce the grafted cellulose paper with a grafting ratio ranging from 96 to 150 % and a contact angle over 127°. The modified cellulose paper material showed promising properties for efficient oil/water separations.

Solvent and catalyst-free modification of hyperbranched polyethyleneimines by ring-opening-addition or ring-opening-polymerization of N-sulfonyl aziridines

Ring-opening (polymerization) of N-sulfonyl aziridines with PEI under solvent/catalyst-free conditions allows the atom-economic synthesis of amphiphilic alkylated PEIs and luminescent PEI-graft-polysulfonamide.

Organocatalytic sequential ring-opening polymerization of cyclic ester/epoxide and N-sulfonyl aziridine: metal-free and easy access to block copolymers

Sequential ring-opening polymerization of ε-caprolactone (ε-CL)/propylene oxide (PO) and N-sulfonyl aziridine switched by tosyl isocyanate (TSI) allows the metal-free synthesis of polysulfonamide-based copolymers.