Azines 1,3-dienes

Diethinyl-2,2,6,6-tctrakis-[irifluoromethyl]- E16a/I. 562 (Azine + 1,3-Diene)... 

The first example of a cycloaddition reaction of a multiple bond to a diene was reported in 1917 Surprisingly, it was found that benzal azine adds to 2 equivalents of several unsaturated systems, when offered in excess, to yield bicyclie compounds. This reaction was named criss-cross" cycloaddition [190], Exploitation of the preparative potential of criss-cross cycloaddition began only in the early 1970s, when hexafluoroacetone azine became available on a larger scale [191,192] The study of this reaction proved to be an impetus tor the development of azine chemistry [183, 193]... 

Hexafluoroacetone azine reacts with 2 equivalents of terminal olefins [194] and acetylenes [182] to give 1,5-diazabicyclo[3.3.0]octanes and 1,5-diazahicy-clo[3 3 0]octa-2,6-dienes, respectively (equation 44). 

Furthermore, azines as a diene system were used for cocyclization with butadiene to form 12-membered heterocyclic compounds as 9 (/1) ... 

Acetic anhydride, with 2-hep-tanone to give 3-n-butyl-2, 4-pentanedione, 51, 90 ACETIC FORMIC ANHYDRIDE, 50, 1 Acetone azine, 50, 2 ACETONE HYDRAZONE, 50, 2, 28 Acetophenone, 54, 93 as sensitizer for irradiation of bicyclo[2.2.1]hepta-2,5-diene to give quadricyclane,... 

Bei der Mischoligomerisation von Keton- oder Aldehyd-azinen mit 1,3-Butadien entstehen 1,2-Diaza-l, 5,9-cyclododecatriene2. Hierbei werden Nickel-Katalysatoren mit oder ohne zusatzliches Phosphan oder Phosphit verwendet das Mol-Verhaltnis von 1,3-Buta-dien zu Azin betragt 3 1 bis 10 1 z. B. ... 

Other imino derivatives arise, as by-products or in side reactions, on heterocyclization. Thus, the treatment of cinnamoyltropolones 75 with hy-droxylamine (Scheme 19) yields, in the case of the 5-nitro derivative, the corresponding isoxazolotroponeoxime (89JHC371). The formation of oximes and several hydrazones from 3-acetyltropolone or its derivatives has also been mentioned (Section II,A,3,c). Moreover, an azine was obtained in addition to quinoxalotropone 213 (Section II,B,2,c) a tropone immonium salt was isolated after an extremely complex diene reaction of an 6-amino-2-azaazuIene (93CB441). 

The analogous cycloadducts 10,11 and 13 were obtained from the dienes (E,E)-7, (E,Z)-7, and (F)-12, respectively, by reaction with 4-phenyl-(3//)-l,2,4-triazole-3,5(4//)-diones52 53. Pyrid-azine-3,6-dione and phthalazine-2,5-dione show comparable reactivity and diastereoselectivi-ty 52. A series of 3,6-disubstituted tetrahydropiperazines were in turn prepared from the primary cycloadducts 10 and 11 with notable 1,4-stereoinduction 53. 

Nitroso compounds generally react as dienophiles with 1,3-dienes to give 3.6-dihydro-2//-1,2-ox-azines 1 through a [4 -I- 2] addition proceeding in a stereoselective cis mode. The overall process, carried out on cyclic or 1,4-disubstituted dienes, consists of a diastereoselective 1,4-oxyamination of the diene moiety1 - 3. 

Reaction with conjugated dienes Sodium hydrazide in the presence of hydrazine reacts with isoprene to form the azine (1) and the pyrazole (2). 

A variety of 1-aryl-2-vinylcyclopropanes with a heterocyclic aryl group have been prepared by direct photolysis of the corresponding aryldiazomethanes in the corresponding but-1,3-dienes. All the heteroarylcarbenes employed, viz. pyridylcarbene, furylcarbene and thienylcar-bene, gave low yields (< 15 /o) of cyclopropanes. The main product was the corresponding azine, but minor amounts of stilbene were also obtained. Thus, when 2-furyldiazomethane was irradiated in but-1,3-diene at — 40°C furfuralazine (20c) was isolated in 18% yield, l-(2-furyl)-2-vinylcyclopropane (21c, R = H) was obtained in 8% yield, and 1,2-bis(2-furyl)ethene (22c, R = H) was formed in 0.8 /o yield. ... 

Hexafluoroacetone azine undergoes cycloaddition reactions with various electron-rich olefins or 1,3-dienes at moderate temperature to givepyridazines [Eq. (6)]. Depending on the structure and the quantity of the olefin employed and the temperature, other mono or bicyclic heterocycles can be formed. 

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