Pyrazole 1.3.5- trimethyl

Pyrazole, 3-(trifluoromethyl)-4,5-trimethylene as amebicide, 5, 291 Pyrazole, 3-triflyl-4-phenyl-synthesis, 5, 282 Pyrazole, 1,3,4-triiodo-synthesis, 5, 234 Pyrazole, 1,3,5-trimethyl-isomerization, 5, 221 Pyrazole, 3,4,5-trimethyl-bromination, 5, 240 halogenation, 5, 89 reactions... 

JA173) illustrates this possibility (Scheme 34). Thus 3,3,5-trimethyl-3//-pyrazole (371 R = H) on irradiation in pentane solution gives 1,3,3-trimethylcyclopropene (372 R = H) the intermediate diazoalkene (373) has been characterized. The tetramethyl derivative (371 R" = Me) when irradiated at -50 °C in methylene chloride leads to a species believed to be a l,2-dlazablcyclo[2.1.0]pent-2-ene (374). This isomerization is thermally reversible, the 3H- pyrazole being regenerated at room temperature. 

HNMR, 5, 186 (B-73NMR165, B-76MI40402) Pyrazole, 3,4,5-trimethyl- HNMR, 5, 184 (B-76MI40402, B-73NMR165) pAC, 5, 223 (68BSF707, 68BSF5009)... 

Phosphetanium tetrachloroaluminum salt, 1-chloro-2,2,3-trimethyl-1-phenyl-synthesis, 1, 524 Phosphindole synthesis, 1, 517 Phosphine, pyrazol-l-yl-synthesis, 5, 236 Phosphirane, 1-phenyl-synthesis, 1, 525 Phosphirane, 1,2,3-tri-t-butyl-... 

Pyrazole, N-vinyl-polymerization, 5, 269 3H-Pyrazole, 3,3,5-trimethyl-irradiation, 5, 251 Pyrazole carbaldehydes reactions, 5, 260 Pyrazole carbinols dehydration, 5, 261... 

Pyrazole and its 3,5-dimethyl and 3,4,5-trimethyl derivatives combined with two moles of dimethyl acetylenedicarboxylate giving products of similar ultraviolet absorption spectra to the parent pyrazoles. These products [e.g., (69)] do not possess the strong broad absorption at ca. 3.20 /u, characteristic of the bonded N—H group which is present in the parent pyrazoles and are formed by two successive Michael addition reactions. In the case of 3,5-dimethylpyra-zole, the initial fumarate (68) has been isolated and possessed a more conjugated type of absorption spectrum to those of the dipyrazolyl-... 

When methylene chloride was used as a solvent, it was found that 28 are obtained in minor amounts, while the dominating product is the -coordinated chloro-carbyne species [(> -Tp )Mo(CO)2(=CCl)], whose yield increases abruptly with substitution in the pyrazol-l-yl fragments (3-methyl-, 3,4,5-trimethyl-, and 3,5-dimethyl-4-chloro derivatives) [90AX(C)59,95JCS(D) 1709]. The tungsten analog can be prepared similarly. The chlorocarbyne molybdenum complex follows also from the reaction of the parent anion with triphenylsulfonium cation but conducted in dichloromethane. The bromo- and iodocarbyne derivatives are made similarly. 

Cyclische N-Acyl-hydrazone mit einer cnr/o-Hydrazinocarbonyl-Gruppe ergeben ahnlich den entsprechenden Carbonsaure-hydraziden keine einheitlichen Reduktions-produkte. Im Gegensatz zu den acyclischen Acyl-hydrazonen werden hauptsachlich cyclische Hydrazone gebildet. 5-Oxo-3,4,4-trimethyl-l-phenyl-4,5-dihydro-pyrazol er-gibt z. B. 50% d.Th. 3,4,4-Trimethyl-l-phenyl-4,5-dihydro-pyrazol und 20% d.Th. 5-Hydroxy-3,4,4-trimethyl-1 -phenyl-4,5-dihydro-pyrazoV ... 

Zu einer Losung von 4,93 g (0,13 Mol) Lithiumalanat in 100 ml abs. Diathylather wird unterRiihren und un-ter Stickstoff vorsichtig eine Losung von 10 g(0,05 Mol) 3,5,5-Trimethyl-1-acetyl-4,5-dihydro-pyrazol in 20 ml abs. Diathylather gegeben. Man kocht 1 Stde. unter RiickfluB, kiihlt ab, versetzt mit Wasser, saugt ab, wascht mit Diathylather, trocknet das Filtrat mit Kaliumcarbonat und engt ein. Der Riickstand wird i. Vak. destilliert Aus-beute 5,2 g (60°/, d.Th.) Kp2li 63-64°. 

The enantioselective hydrosilylation catalyst system based on the chiral pre-catalyst dichloro l- (/ )-l- [(S)-2 (dipheaylphosphinoKP) ferrocenyl] ethyl -3- trimethyl- phenyl-5-1 H- pyrazole-tc/V) palladium, 1 (shown in Figure 2) exhibits a interesting inversion of selectivity with a series of para-... 

As reported by Steel et al. three structural isomers of bis(camphor-pyrazol-l-yl)methane (21a, 21b and 21c) are formed by coupling of camphorpyrazole 10 [i.e., (4S,7i )-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-l(2)H-indazole] with CH2CI2 (121). Isomer 21c can be separated from the other two structural isomers by crystallization or column chomatography. Deprotonation at the bridging carbon atom, subsequent reaction with carbon dioxide and acidic workup yields the enantiopure bis(camphorpyrazol-l-yl)acetic acid Hbpa (8) (Scheme 17, Fig. 19) (116). Due to missing substituents at the p5rrazolyl carbon C5 and a hence likely ortho metallation, isomers 21a and 21b are not suited for his reaction (72). 

Metalation of 2 with lithium diisopropylamide (LDA) generates diazo(trimethyl-silyl)methyl hthium (3), which reacts with a,p-unsaturated nitrile 36 and phenyl-sulfones (37) to form 3(or 5)-trimethylsilyl-l//-substituted pyrazole 4 that can be desilylated to furnish pyrazoles 5 (Scheme 8.3). 

Hrf.N C(CH,).C(NOj G.N N.NH6c(NO.,).-C(CH3) NilH mw 295.23, N 42.72% yel crysts, mp 151-2°, dec violently with evolution of gas dissolves in dil NaOH giving an intense violet-red soln, which on acidification reppt the compd unchanged insol in aq alk carbonates was prepd by treating 3-methyl-4-nitro-5-amino -pyrazole in HC1 at 0° with NaN02 and Na acetate for several hours. This compd forms an orn-red Silver salt reacts with diazomethane to form the trimethyl deriv, a yel compd, mp 163-4° (dec) and with phenylisocyanate,... 

The extension of this reaction to include the conversion of 3H-pyrazoles into cyclopropenes is established.86 3,3,5-Trimethyl-3/i-pyrazole (100 R = H), for example, on photolysis in pentane solution gives 1,3,3-trimethylcyclopropene (101), and an intermediate diazo-alkene (102) has been characterized. The proposed conversion of the diazoalkene into the cyclopropene (101) via a vinylcarbene has a... 

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