Karlheinz Gilbert

[7+2]- and [11+2]-cycloaddition reactions of diazo-azoles with isocyanates to azolo[5,1-d] [1,2,3,5] tetrazine-4-ones

Abstract Diazo-azoles react as 1,7- or 1,11-dipoles with isocyanates to form the hitherto unknown pyrazolo[5,1-d] [1,2,3,5]tetrazine-4-ones, [1,2,3,5]tetrazino[5,4-b]indazole-4-ones and [1,2,3]triazolo[5,1-d][1,2,3,5]tetrazine-4-ones in a [7+2]- or [11+2]-cycloaddition reaction.

[7+1]- and [11+1]-Cycloreactions of diazo-azoles with 1-nucleophile-1-electrophiles (ylides) to 3H-pyrazolo[5,1-c][1,2,4]triazoles and 3H-[1,2,4]triazolo[4,3-b]indazoles

Zusammenfassung Diazo-azoles react as 1,7- or 1,11-dipoles with ylides such as diazo-alkanes or such of the phosphonium-, sulfonium0, pyridinium- and sulfene-type to form 3H-pyrazolo[5,1-c][1,2,4]triazoles and 3H-[1,2,4]-triazolo[4,3-b]indazoles in a [7+1]- or [11+1]-cycloreaction.

[3+2]-cycloreactions of 1,2-diacylcyclopropenes with ynamines. Aminofurane- versus aminocyclopentadiene-formation

Abstract Electron deficient 1,2-diacylcyclopropenes represent synthetic equivalent for both acylcarbenes and vinylcarbenes; in their cycloreaction with ynamines aminofuranes and/or aminocyclopentadienes are formed.

Photochemically induced [4+2]- versus [3+2]-cycloreversion reaction of hexasubstituted 2,3-diaza-bicyclo[3.1.0]hex-2-enes☆

Abstract Hexasubstituted 2,3-diaza-bicyclo[3.1.0]hex-2-enes containing large substituents at C-4 and C-6 upon irradiation undergo a novel [4+2]cycloreversion reaction leading to 2,3-diazahexatriens besides the normal [3+2]cycloreversion.