Rearrangements bis

Scheme 13 may look unfavorable on the face of it, but in fact the second two reactions are thermally allowed 10- and 14-electron electrocyclic reactions, respectively. The aromatic character of the transition states for these reactions is the major reason why the benzidine rearrangement is so fast in the first place.261 The second bimolecular reaction is faster than the first rearrangement (bi-molecular kinetics were not observed) it is downhill energetically because the reaction products are all aromatic, and formation of three molecules from two overcomes the entropy factor involved in orienting the two species for reaction. 

ALLYLIC REARRANGEMENT Bis(trimethyl-silyl)peroxide-Vanadyl acetylacetonate. 

However, the different configurations i may also directly rearrange, Bi Bx... 

Primary products are the symmetrical aldazines 56. Their N-acylation leads to the bis(N-acyl)enamines 57, which undergo thermal [3,3]-sigmatropic rearrangement ( bis-aza-CoPE rearrangement ) to give the bis-(N-acyl)imines 58 cyclization of 58 leads to the N-acylpyrroles 54 by elimination of benzamide. 

A similar synthesis starts from commercially available 1,5-hexadiyne and 2-methyl-cyclopent-2-enone. The benzocyclobutene is obtained from a bis-acetylene in a cobalt-catalyzed reaction. It rearranges regio- and stereoselectively to a 3-deoxy steroid derivative. The overall yield from the cyclopentenone was 40% (R.L. Funk, 1977). 

The reaction of cyclohexene with the diazopyruvate 25 gives unexpectedly ethyl 3-cyclohexenyl malonate (26), involving Wolff rearrangement. No cyclo-propanation takes place[28]. 1,3-Dipolar cycloaddition takes place by the reaction of acrylonitrile with diazoacetate to afford the oxazole derivative 27[29]. Bis(trimethylstannyl)diazomethane (28) undergoes Pd(0)-catalyzed rearrangement to give the A -stannylcarbodiimide 29 under mild conditions[30]. 

Bis(2-Chloroethyl) 2-Chloroethylphosphonate. The commercial product, Albright Wilson s Antiblaze 78, is a mixture having various related higher boiling diphosphonates. This product is made by the Arbuzov rearrangement of tris(2-chloroethyl) phosphite [140-08-9] ... 

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

Pyridazin-3(2H)-ones rearrange to l-amino-3-pyrrolin-2-ones (29) and (30) upon irradiation in neutral methanol (Scheme 10), while photolysis of 5-amino-4-chloro-2-phenylpyridazin-3(2H)-one gives the intermediate (31) which cyclizes readily to the bis-pyridazinopyrazine derivative (32 Scheme 11). 

In addition to (461), Dorn has described the imine (463) isolated from 5-amino-l-methylpyrazole and arenesulfonyl chloride (80CHE1). Upon heating, or in the presence of triethylamine, it undergoes rearrangement to the more stable 5-bis(arylsul-fonamido)pyrazoles (464). 5-Iminopyrazolines (461) react with acyl chlorides at the exocyclic nitrogen atom to afford amidopyrazolium salts (B-76MI40402). 

Electron deficient species can attack the unshared electron pairs of heteroatoms, to form ylides, such as in the reaction of thietane with bis(methoxycarbonyl)carbene. The S —C ylide rearranges to 2,2-bis(methoxycarbonyl)thiolane (Section 5.14.3.10.1). A"-Ethoxycar-bonylazepine, however, is attacked by dichlorocarbene at the C=C double bonds, with formation of the trans tris-homo compound (Section 5.16.3.7). 

Bismuth heterocycles, 1, 539-561 Bismuthiol I metal complexes, 6, 565 IR spectra, 6, 552 ring structure, 6, 561 structure, 6, 557 Bismuthiol II metal complexes, 6, 565 IR spectra, 6, 552 Bisnorisopenicillin, 7, 332, 333 Bisnorpenicillin V, 7, 331 Bis( l,3,4-oxathiazol-2-ones) applications, 6, 945 Bisoxiranes synthesis, 7, 42 Bi(spiroisoxazolines) synthesis, 6, 108 Bi(spirophosphoranes) polytopal rearrangements, 1, 529 reactions, 1, 535 Bispyranones synthesis, 3, 793 a,oj-Bispyranones, alkylene-irradiation, 3, 678... 

Distannacyclodecanes synthesis, 1, 606 Disulfide, benzylpurinyl ribosylation, S, 560 Disulfide, bis(l-alkenyl) rearrangement thiophenes from, 4, 871 Disulfide, bis(4-phenyl-3-butenyl) cyclization, 4, 867-868 Disulfide, dibenzothiazolyl as vulcanization accelerator, 1, 402 Disulfide, di(2,6-dimethoxypyrimidin-4-yl) oxidation, 3, 96 Disulfide, dipyrimidinyl synthesis, 3, 137 Disulfide, di(tetrazol-5-yl)... 

Methane, bis(2-acetyl-l-pyrrolyl)-photoisomerization, 4, 203 Methane, bis( 1 -aryltetrazol-5-yl)dichloro-rearrangement, 5, 824 Methane, bispyrrolyl-synthesis, 4, 274 Methane, bis(2-pyrrolyl)-oxidation, 4, 271 reactions... 

Oxazolidin-5-one, bis(trifluoromethyl)-reactions, 6, 213 Oxazolidinones polymers, 1, 281-282 reactions, 6, 213 Oxazolidinones, imino-rearrangement, 5, 775 Oxazolidinones, vinyl-polymers, 1, 281 Oxazolidin-2-ones circular dichroism, 6, 185 H NMR, 6, 181 IR spectroscopy, 6, 183 PE spectroscopy, 6, 183 reactions, 6, 213... 

Thiirene, 2-acetyI-3-methyl-rearrangement, 7, 143 Thiirene, 2,3-bis(trifluoromethyl)-photolysis, 7, 142 Thiirene, 2,3-diaryl-... 

Trimethylacetaldehyde reacts with sulfur tetrafluoride with a skeletal rearrangement 2,3-difluoro-2-methylbutane is formed in high yield as the only fluo-roalkane along with bis(l-fluoro-2,2-dimethylpropyl) ether [169] (equation 85)... 

Sulfur tnoxide adds to 2,2 difluoroethylenesulfonyl fluoride to afford the P sultone and its rearrangement product, bis(fluorosulfonyl)acetyl fluoride Potassium fluoride acts as a base and reacts with the acetyl fluoride to eliminate the elements of hydrogen fluoride and produce bis(fluorosulfonyl)ketene [IS] (equation 6)... 

In contrast to diamino/urazan, diamino/uraxan is probably unstable. All attempts to generate it from rearrangements shown in Scheme 107 failed. However, Curtius rearrangement of 3,3 -bis(azidocarbonyl)-4,4 -azofuroxan 182 with subsequent isomerization afforded 4,4 -diamino-3,3 -azofuroxan 183 in 69% yield (Scheme 108) (98DOK499, 98MI2, 98MI6). 

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