Total Synthesis of (-)-Merochlorin†A.

The first asymmetric total synthesis of the meroterpenoid (-)-merochlorin A is described. The route features enantiospecific gold-catalyzed tandem 1,3-acyloxy migration/Nazarov/aldol reaction sequence to furnish the bicyclo[3.3.0]octane core in a single step from a linear propargylic 1,3-enyne aldehyde. After completion of the central skeleton by reductive enol lactone rearrangement, late stage Diels-Alder cycloaddition/aromatization sequence installed the resorcinol. An additional salient feature of the synthesis is the assignment of the absolute configuration, which had not been determined previously.

Di(1H-tetrazol-5-yl)methane as Neutral Ligand in Energetic Transition Metal Complexes.

The synthesis of di(1H-tetrazol-5-yl)methane (1, 5-DTM), starting from commercially available sodium azide and malononitrile, is described. This tetrazole was characterized and investigated for use as a neutral nitrogen-rich ligand in various energetic transition metal complexes: ([CuCl2(5-DTM)2]·2H2O (2), [Co(H2O)2(5-DTM)2]Cl2 (3), [Ni(H2O)2(5-DTM)2]Cl2 (4), [Co(H2O)2(5-DTM)2](NO3)2 (6), [Ni(H2O)2(5-DTM)2](NO3)2 (7), [Zn(H2O)2(5-DTM)2](NO3)2 (8), {[Cu3(SO4)2(5-DTM-H)2(H2O)4(5-DTM)2]·2H2O}∞ (9), [Cu(H2O)2(5-DTM)2](NO3)2 (11), [Cu(NO3)2(5-DTM)2]·2H2O (12), [Cu(NO3)2(5-DTM)2] (13), [Cu(H2O)2(5-DTM)2](ClO4)2 (14), and [Cu(ClO4)2(5-DTM)2] (15). Obtained coordination compounds were characterized using single crystal X-ray diffraction (except for 7 and 13), IR spectroscopy, elemental analysis, and differential thermal analysis. The sensitivities to external stimuli (impact, friction, electrostatic discharge) were determined. Complexes 12 and 13 were tested for their ignitability by laser irradiation.

Cobalt-Catalyzed Aerobic Aminocyclization of Unsaturated Amides for the Synthesis of Functionalized γ- and δ-Lactams.

We report the cobalt-catalyzed aminocyclization of unsaturated N-acyl sulfonamides in the presence of oxygen to provide γ- and δ-lactam aldehydes. Use of an optically active cobalt catalyst resulted in the formation of enantiomerically enriched γ-and δ-lactam alcohols. The γ-lactam aldehydes and alcohols obtained were elaborated into useful building blocks.

Organophotocatalytic carbo-heterofunctionalization of unactivated olefins with pendant nucleophiles.

We report the difunctionalization of unactivated, terminal olefins through intermolecular addition of α-bromoketones, -esters, and -nitriles followed by formation of 4- to 6-membered heterocycles with pendant nucleophiles. The reaction can be conducted with alcohols, acids, and sulfonamides as nucleophiles furnishing products bearing 1,4 functional group relationships that offer various handles for further manipulation. Salient features of the transformations are the use of 0.5 mol% of a benzothiazinoquinoxaline organophotoredox catalyst and their robustness with respect to air and moisture. Mechanistic investigations are carried out and a catalytic cycle for the reaction is proposed.