4-Pyridylnitrene and 2-pyrazinylcarbene

• Curt Wentrup,
• Ales Reisinger and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 754–760, doi:10.3762/bjoc.9.85

• Curt Wentrup Ales Reisinger David Kvaskoff School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia 10.3762/bjoc.9.85 Abstract Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5-a

• -diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27. Keywords: carbene–nitrene interconversion; diazepines; flash vacuum thermolysis; matrix photochemistry; nitrile ylides; reactive intermediates; Introduction The carbene–nitrene interconversion exemplified with

• vacuum thermolysis (FVT) conditions cyanocyclopentadiene 6 is formed (Scheme 1). Several other carbene–nitrene rearrangements have been reported [3][4][5]. In addition to the ring expansion (1–2–3), two ring opening reactions have been investigated in recent years. Type I ring opening takes place in

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

• Curt Wentrup,
• Nguyen Mong Lan,
• Adelheid Lukosch,
• Pawel Bednarek and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 743–753, doi:10.3762/bjoc.9.84

• Universität Marburg, D-3550 Marburg, Germany 10.3762/bjoc.9.84 Abstract Precursors of 3-pyridylnitrene and 2- and 4-pyrimidinylcarbenes all afford mixtures of 2- and 3-cyanopyrroles on flash vacuum thermolysis, but 3-cyanopyrroles are the first-formed products. 3-Quinolylnitrenes and 4-quinazolinylcarbenes

• either the nitrenes or the diazacycloheptatetraenes to nitrile ylides. Keywords: carbene-nitrene interconversion; diazepines; flash vacuum thermolysis; matrix photochemistry; nitrile ylides; reactive intermediates; Introduction A multitude of rearrangements of heterocyclic nitrenes have been described

• ) under conditions of photolysis in solution or in matrices as well as under flash vacuum thermolysis (FVT) (Scheme 2) [1][7][8][9][10]. The end products under FVT conditions are the 2- and 3-cyanopyrroles 7 and 8 [10][11]. A competing ring-opening of 2-pyridylnitrenes to cyanobutadienylnitrenes can lead

Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0]nonadiene

• Sabine Leber,
• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2012, 8, 738–743, doi:10.3762/bjoc.8.83

• signals for bisdioxine and tetraoxaadamantane units were made in agreement with previously reported data [1][2][3][4][5][6][7][15]. 1,3,5,7-Tetra-tert-butyl-2,6,9-trioxabicyclo[3.3.1]nona-3,7-diene-4,8-dicarbonyl dichloride (3): Flash vacuum thermolysis of 5-tert-butyl-4-pivaloylfuran-2,3-dione generates