Criss-cross reaction

Reaction of secoestrone aldehyde 306 with half an equivalent of hydrazine hydrate led to aldazine 307, which undergoes a criss-cross reaction in the presence of BF3-OEt2 to furnish a decacyclic pyrazolidine derivative 308 in 74% yield (Scheme 44) <2002T6843>. 

Non-classical criss-cross reaction A parallel tandem cycloaddition. Formation of imidazo[1,5-b] [l,2,4]triazoles... 

Classical" criss-cross reaction antiparallel tandem cycloaddition... 

Non-classical" criss-cross reaction parallel tandem cycloaddition Scheme 2 Criss-cross reactions. The Classical criss-cross reaction, an antiparallel tandem cycloaddition of azines 9 and heterocumulenes 10 (upper equation). The Non-classical" criss-cross reaction, a parallel tandem cycloaddition of azoalkenes 5 and thiocyanic acid 6 (lower equation). 

The criss-cross reaction of azoalkenes is restricted to the addition of thiocyanic acid and could not be extended to cyanic acid, as this is the case in the classical reaction with azines. However, the cycloadduct expected to arise from the reaction of an azoalkene with cyanic acid, the heterobicyclic 2,5-dione 13, can be obtained simply by reacting the 2,5-dithiones 8 with hydrogen peroxide in sodium hydroxide (Scheme 3) (93TH, OITH). 

However, the structures of the isolated products formed upon elimination of one molecule of HNCY are not the expected azomethine imines 7 (X = S) and 14 (X = S), respectively instead, the corresponding tautomers, enehydrazines 15 (X = S) and 16 (X = O) resulting from a 1,4-H shift are formed (Scheme 3) (93TH, OITH). At higher temperature, the criss-cross reaction is completely reversed to give the parent azoalkene 5. 

This tandem reaction resembles a new variety of the criss-cross reaction (with respect to the relative regiochemistry of the added thiocyanic acid this reaction is a parallel criss-cross reaction as opposed to the antiparallel cycloaddition of heterocumulenes to azines in the classical crisscross reaction). 

Reactions of azines and imines (including criss-cross cycloaddition) 76S349... 

Burger s criss-cross cycloaddition reaction of hexafluoracetone-azine (76S349) is also a synthetic method of the [CNN + CC] class. In turn, the azomethines thus produced, (625) and (626) (79LA133), can react with alkenes and alkynes to yield azapentalene derivatives (627) and (628), or isomerize to A -pyrazolines (629) which subsequently lose HCF3 to afford pyrazoles (630 Scheme 56) (82MI40401). 

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]... 

Because the criss-cross cycloaddition reaction is a sequence of two [3+2] cycloaddition steps, the reaction with a,co-diolefins offers a new entry into macro-molecular chemistry New types of polymers with interesting structures and prop erties can be synthesized [213, 214, 215] (equation 48)... 

Simple criss-cross cycloadditions described so far are in fact limited to aromatic aldazines and cyclic or fluorinated ketazines. Other examples are rather rare, including the products of intramolecular criss-cross cycloaddition. The criss-cross cycloadditions of hexafluoroacetone azine are probably the best studied reaction of this type. It has been observed that with azomethine imides 291 derived from hexafluoroacetone azine 290 and C(5)-C(7) cycloalkenes < 1975J(P 1)1902, 1979T389>, a rearrangement to 177-3-pyrazolines 292 competes with the criss-cross adduct 293 formation (Scheme 39). 

The reaction of hexafluoroacetone azine with cycloheptatriene at 70 °C provides after 8 days a mixture containing 28% of unchanged azine 290 and products formed by three distinct mechanistic pathways, that is, criss-cross cycloaddition product 294, a bis-ene adduct 295 and its oxidation product 296, and [3+6] cycloaddition leading to diaziridine 297, in the ratio 15 38 7 (Scheme 40) <1995JFC(73)203>. 

The reaction of quadricyclane with hexafluoroacetone azine 290 under similar conditions affords a mixture of a 1 1 adduct 298, the o , -bis-cycloadduct 299 formed by reaction of the C=N bond in 298 with quadricyclane, and the criss-cross addition product 300 (Scheme 41) <1995JFC(72)147>. 

The criss-cross addition of azines of aromatic aldehydes with various electron-deficient olefins in which the double bond is terminal, for example, methyl acrylate, acrylonitrile, or in which allylic substituents do not sterically hinder the reaction, for example, maleic anhydride, is well known and was duly covered in CHEC-II(1996)<1996CHEC-II(8)747>, as well as in a review <1997ALD97>. Recently, the reaction has been used for the preparation of hyperbranched polymers <1998MI2655, 2002MAC712>. 

Some examples of the lateral cyclization of suitable O-allyl and O-propargyl derivatives were discussed in CHEC-11(1996) <1996CHEC-II(8)747>. Thermal reaction of silyl diazoacetate 303 in xylene provides unspecific decomposition and a minor amount (about 2%) of a colorless solid can be precipitated with ether. The X-ray diffraction analysis identified the structure 305, which is a product of the lateral criss-cross cycloaddition of primarily formed azine 304 (Scheme 43) <2000T4139>. 

Thermally induced intra-intermolecular criss-cross cycloaddition of nonsymmetrical azines 363 in the presence of phenyl isocyanate provides the corresponding products of the mixed criss-cross cycloaddition 364 (Scheme 55) <2002TL6431>. Two different reaction mechanisms, intra-intermolecular and inter-intramolecular, of the mixed criss-cross cycloaddition with opposite sequence of reaction steps are possible. Quantum chemistry calculations suggest the intra-intermolecular mechanism as the most probable mechanism of this reaction <2004CCC231>. 

With benzaldazine, a criss-cross-type cycloaddition takes place reaction with diphenyldiazomethane yields a bicyclic phosphirane (49) among other products <87CB597). 

Rees and co-workers in their study of the reactions of trithiazyl trichloride in the preparations of heterocyclic compounds have noted that the isothiazolo[5,4-, isothiazole compound 140 was produced in low yield on reaction with conjugated dienes, along with the other heterocyclic systems 142-145 in much higher yields (Equation 28). Since it is known that trithiazyl trichloride is in thermal equilibrium with its monomer NSCl (Equation 29), the authors propose the so-called criss-cross cycloaddition reaction (Equation 30) which has been reported for azabu-tadienes, but this represents the first example of such a criss-cross cycloaddition to an all-carbon diene <1998CC1207>. 

In his supplement to Syllabus, Dunkle remarked (Ref 22, p lid) that schlieren photography of deton waves in 40/60 C2H2/O2 initially at 1/4 atm showed a wavy pattern of criss-crossing dark diffuse lines behind the front. Fay Opel (Ref 17) calculated that if these lines are a weak wake of Mach waves in supersonic flow, the flow of the burnt gases with respect to the front is Mach 1.14 rather than Mach 1.00 as in a C-J process. However, at this pressure the reaction is complete within a fraction of a millimeter behind the front, and the flow could very well accelerate to Mach 1.14 with density decrease below the C-J value. Fay Opel traced the effect to the boundary layer. 

Ando and coworkers have described unusual photochemical behavior of a bis-diazo compound 263 which on photolysis gave rise to a bis-silene 264135. In inert solvents this spontaneously underwent two modes of reaction, criss-cross (head-to-tail) addition and parallel (head-to-head) addition, leading to bridged disilacyclobutanes 265 and 266 (Scheme 47). 

The so-called criss-cross additions of azines involve a sequence of two 1,3-dipolar cycloaddition reactions, as exemplified by the reactions of hexafluoroacetone azine and benzaldazine with DMAD and phenyl isocyanate (Scheme 9) (76S349). 

Pyrazolo[l,2- ]pyrazole systems 166 can be obtained by the reaction of hydrazine with acrylic esters (Scheme 99) <2001J(P2)243, CHEC-III(12.10.12.1)406>. The betaines 167 reacts with dimethyl acetylenedicarboxylate to give products 168 which easily undergo thermal fragmentation to 169 followed by another cycloaddition to form 170 (Scheme 100) <1981JA7743>. Criss-cross addition of azines, e.g. 171, also involves two successive 1,3-dipolar cycloadditions to give pyrazolo[l,2-. 

Diazoacetic acid silyl esters can be prepared by fra t-esterification of tert-butyl diazoacetate with trialkylsilyl triflate <1985JOM33>. Analogously prepared (alkenyloxy)silyl 203 and (alkynyloxy)silyl diazoacetates 206 underwent silicon-tethered 1,3-dipolar cycloaddition reactions as shown in Scheme 37 and Equation (38). Compound 205 resulted from a lateral criss-cross cycloaddition of the intermediate azine 204, which was formed from two molecules of 203 by diazo + diazo or diazo + carbene reaction <2000T4139>. On the other hand, when silyl diazoacetates 206 were kept in xylene at 142 °C for 1 h, bicyclic pyrazoles 207 were obtained (Equation 38). 

Corrosion inhibitors, [1.2,4]triazino[4,3-ojbenzimidazoles, 59, 155 Coulson-Rushbrook theorem, 55, 273 Coumarins, see l-Benzopyran-2-ones Coupling reactions, trifluoromethyl iodide with aryl halides, 60, 12 Covalent hydration in 6-nitro-l 1,2,4]triazolo[ 1,5-a)-pyrimidines, 57, 107 of coordinated ligands, 58, 138 Creutz-Taube ion, 58, 124 Criss-cross cycloadditions, of... 

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