Organic syntheses via transition metal complexes. 96. 1-azacycloalkene and 2-azabicycloalkene derivatives of 4-amino-1-metalla-1,3-dienes by reaction of saturated lactims with (1-alkynyl)carbene complexes of chromium and tungsten

Reaction of five- and six-membered O-alkyl lactims similar to(CH2)(n)-N=C(OR)similar to 5 (n = 3) and 7 (n = 4) with (1-alkynyl)carbene complexes (CO)(5)M=C(OEt)C=CPh 1 (a, M = Cr; b, W) gives binuclear 1-alkoxy-2-azabicyclo[n.2.0]alkene derivatives (E)-6 and (E)-8, respectively, in 90-94% yields. Reaction of seven- and eight-membered O-alkyl lactims similar to(CH2)(n)-N=C(OR)similar to 9 (n = 5) and 11 (n = 6) with compounds 1 affords mononuclear 4-(1-aza-cyclo-2-alken-1-yl) 1-metalla-1,3-butadienes (E)-10 and (E)-11, respectively, but no binuclear derivatives, Both mono- and binuclear metal compounds undergo fast transformations on contact with silica gel. Chromatography of the binuclear tungsten compound (E)-6b on silica gel results in fragmentation of the (cyclobutenyl)carbene unit to give 1,11-bis(tungsta)-5-azaundeca-1,3,6,8,-10-pentaene (13) as well as in hydrolysis of the 2-alkoxy pyrrolidine unit with formation of a bis(carbene) derivative 15 of an amino acid. Compound 13, on extended contact with silica gel, undergoes cyclization and subsequent hydrolysis to 2-azabicyclo[3.3.0]octenone 14, Thermal fragmentation of the mononuclear dihydroazepine compound (E)-10c affords dihydro- and tetrahydropyrrolo[1,2a]azepines 17 and 18, respectively, X-ray crystal structural data are reported for the binuclear compound (E)-6b as well as for mononuclear compounds (E)-10c and 14.