DBU-mediated cleavage of aryl- and heteroaryl disulfides

Abstract

The capacity of the nitrogen nucleophile, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to reduce aryl-and heteroaryl disulfides to the corresponding mercaptans is demonstrated. While dicarboxylated disulfide analogues afford the mono-DBU disulfide salts, as confirmed by X-ray crystallography, the corresponding methyl esters are cleaved normally.

Synthesis of New Azetidine and Oxetane Amino Acid Derivatives through Aza-Michael Addition of NH-Heterocycles with Methyl 2-(Azetidin- or Oxetan-3-Ylidene)Acetates

“…Various methods for the aza-Michael addition reaction have been developed using a variety of promoters, such as inorganic and organic bases, proton acids, Lewis acids, and enzymes [ 49 , 50 , 51 , 52 ]. Aza-Michael addition greatly benefits from its mild reaction conditions, and the choice of a non-nucleophilic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) helps to prevent side reactions, for example, the cleavage of the ester group, which can be caused by other strong bases such as hydroxides [ 53 , 54 , 55 ]. Yeom et al developed a convenient method for the preparation of functionalised derivatives from cyclic amines with methyl acrylate through aza-Michael reaction using a sub-stoichiometric amount of DBU as an effective promoter [ 56 ].…”

“…The aza-Michael reaction of benzotriazole with methyl acrylate was reported to form N-1 and N-2 adducts in a mixture of benzotriazol-1-yl-propionic and benzotriazol-2-yl-propionic acid methyl esters by using anhydrous potassium phosphate (K 3 PO 4 ) as a catalyst [ 54 ], while the 1,4-conjugated aza-Michael addition of benzotriazole to dienones catalysed by potassium acetate (KOAc) yielded only the corresponding N-1 isomer [ 56 ]. Recently, Chen et al reported an efficient, regio- and enantioselective aza-Michael reaction for the synthesis of the N-1 isomers from benzotriazole with α-substituted β-nitroacrylates catalysed by a chiral organocatalyst [ 49 ].…”

Mechanisms of Degradation for Polydisulfides: Main Chain Scission, Self-Immolation, Or Chain Transfer Depolymerization

“…To this end, we conducted room temperature polymerization of methyl lipoate (MLA) in the presence of 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU). DBU, but not other common organic amines, reversibly reacts with disulfides, liberating one thiolate from a disulfide. , This reaction provides the required initiating species for MLA polymerization with ensuing propagation of chain growth via thiol–disulfide exchange. We achieved control over the polymer molar mass through the variation of the content of a thiol trap, dithiodipyridine (DTP), added to the polymerization mixture.…”

Regioselective Hydrothiolation of Alkynes by Sulfonyl Hydrazides Using Organic Ionic Base–Brønsted Acid

“…Further, when the resulting disulfide was separately made to react with phenylacetylene under the established conditions, it gave rise to the final product 3e although with a diminished yield. On the basis of isolation of products, control experiments and the existing literature, , a plausible mechanism is outlined in Scheme .…”