Synthesis of poly-substituted benzenes starting from Baylis–Hillman adducts: DBU-assisted unusual dehydrogenation

Umpolung cyclization reaction of N-cinnamoylthioureas in the presence of DBU

A novel regioselective cyclization reaction of N-cinnamoylthioureas leading to six- or five-membered heterocyclic compounds was developed. N-Cinnamoylthioureas in the presence of trifluoroacetic acid (TFA) underwent the well-established intramolecular cycloaddition reaction to give 2-imino-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-ones in good yields. On the other hand, the reaction with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) proceeded in an unprecedented "umpolung" cyclization fashion to afford five-membered 2-imino-1,3-thiazolidin-4-ones and/or 2-thioxoimidazolidine-4-ones. The reaction was considered to occur via a cycloadduct of DBU with the cinnamoyl moiety followed by intramolecular attack of the thiourea group.

Tandem three-component reactions of aldehyde, alkyl acrylate, and dialkylmalonate catalyzed by ethyl diphenylphosphine

A new highly efficient three-component reaction of alkyl acrylate, aldehyde and dialkyl malonate using ethyl diphenylphosphine as organocatalyst has been described. Various highly functional compounds bearing hydroxyl groups and the ester functions can be easily prepared in moderate to good yields according to our one-step procedure. The reactions are believed to proceed via Morita-Baylis-Hillman reactions of alkyl acrylate and aldehydes, followed by the Michael addition reactions of dialkyl malonates. Our reactions indicated that the intermediate species formed in the phosphine-catalyzed MBH reaction are an effective organic base to catalyze the Michael addition reactions of dialkyl malonates to the preformed MBH adducts.

Chemo- and regio-selective functionalization of Morita–Baylis–Hillman bromides with anthranilic acid

Nucleophilic substitution products of Morita–Baylis–Hillman adducts and their derivatives are valuable synthons. In an attempt to ameliorate the functionality of these functionalized motifs, we report the regio- and chemo-selective functionalization of Morita–Baylis–Hillman bromides with anthranilic acid.