Cyclopropyl pyridine

Long range electronic effects sometimes can be discerned. Thus, the striking difference in basicity [4] of 4-cyclopropylpyridine [pKa 6.44] and 4-(2-carbethoxy cyclopropyl)pyridine [pKa 5.58] is attributable to the field effect and through-bond interaction. 

Treatment of (70a) with methanesulfonyl chloride in pyridine gives rise to vinylcylopropane (73) which can be converted back to the homoallylic alcohol (70a) under conditions similar to those used for converting cyclopropyl carbinol (69a) to the B-homo-7)5-ol (70a). 

Cyclopropyl methanols when treated with a combination of hydrogen fluoride, pyridine, potassium hydrogen fluoride, and diisopropylamine undergo fluonnation and rearrangement to give excellent yields of homoallylic fluorides Chlorobenzene substituted cyclopropyl methanols at low temperatures leads to ring expansion to give... 

CN 1 -Cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-[(4a5,7a5)-octahydro-6//-pyrrolo[3,4-fc]pyridin-6-yl]-... 

Formation of rearranged products in the solvolysis of homopropargyl systems need not involve triple-bond participation and vinyl cations in all instances. Ward and Sherman investigated the formolysis of 4-phenyl-1-butyn-l-yl brosylate, 57 (80). At 80°C in the presence of one equivalent of pyridine, they observed formation of phenyl cyclopropyl ketone, 58, and... 

When two equivalents of pyridine were added to the nmr sample and the probe heated to 80° C, the enol formate 61 decreased and phenyl cyclopropyl ketone 58 appeared at a rate approximately ten times faster than in the previous buffered system. The observation of intermediate 61 and the kinetic results, together with the observed induction periods, are consistent with the idea that some and perhaps all of the rearranged product ketone in the solvolysis of this system arises via double-bond participation in 61 rather than triple-bond participation and a vinyl cation (80). 

C-C3H5 = cyclopropyl. m By pyridine ylide method. n By direct observation. 

Thienopyridone derivatives have been prepared to study their potential activity as antibacterials. The greatest activity against Escherichia coli is observed for 2-chloro-7-cyclopropyl-4,7-dihydro-4-oxothieno[2,3- ]pyridine-5-car-boxylic acid <1997H(45)255>. 

Chalcone analogs of pyridine ketones (33) and the corresponding cyclopropyl derivatives 34, which are molecules of biological interest, have been studied (74BSF1427 74BSF1442) by NMR, IR, and UV spectroscopy in their isomeric forms. The N,0-trans conformation prevails in the 2- and 3-substituted pyridines and, in derivative 34, coplanarity of the pyridine ring and carbonyl plane is reported (74BSF1442). 

Moreover, interesting ring-formation reactions to give 7 have also been reported for substituted mclhoxyallenyl(cyclopropyl)methanols using 70% hydrogen fluoride/pyridine in combination with sodium fluoride or potassium hydrogen fluoride.82... 

Chlorohydrins. F.poxides can be cleaved to frotw-chlorohydrins with pyridinium hydrochloride in chloroform or pyridine. The reagent also cleaves a-cyclopropyl ketones to mixtures of y-chloro ketones obtained by the two possible modes of cyclo-propyl ring fission.2... 

Cuprous cyclopropylacetylide, prepared from Cul and cyclopropylacetylene in ammo niacal solution couples with 4-iodonitrobenzene in pyridine, yielding 4-nitrophenyl cyclopropylacetylene (equation 154)234. Reaction of the acetylide with tropylium tetra-fluoroborate in acetonitrile, in the presence of LiBr, affords 7-(cyclopropylethynyl)cyclo-heptatriene. The anion radicals obtained by reduction of these compounds were utilized for ESR spectroscopic analysis of the cyclopropyl P hyperfine splittings. 

Chemical Name 3-Quinolinecarboxylic acid, l-cyclopropyl-6-fluoro-l,4-dihydro-8-methoxy-7-((4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-4-oxo-, monohydrochloride... 

Thermolysis of 2/7-aziridines having cyclopropyl ring substitution yielded pyridines <95H(40)511>. Steric inhibition of pyridine ring formation was noted for some aziridines. Aza-Wittig reaction on aziridines yields tetrahydropyridines <95TL(36)3557>. 

Otherwise, cuprous iodide-catalyzed addition of methylmagnesium iodide to 2-cyclohexen-l-one in ether at 0 °C, followed by trapping of the resultant enolate anion 188 with cyclopropanecarboxaldehyde 189, afforded the two diastereomers of the cyclopropylcarbinol 190 a. Further transformation into the corresponding acetates 190b (acetic anhydride, pyridine), followed by treatment with l,5-diazabicyclo[4.3.0]-non-5-ene (DBN) in refluxing benzene, provided in 78 % yield, a mixture of the desired P-cyclopropyl enones 191 and 192, in a ratio of 13 1, Eq. (60) 127). 

The Simmons-Smith reaction often starts very slowly and proceeds quite slowly at room temperature. The method of the preparation of active zinc-copper couple has been improved 93, 196, 298, 376, 443, 466). The use of zinc dust/cuprous chloride instead of zinc-copper couple gives higher yields in the Simmons-Smith reaction 407). The reaction with homoallylic alcohols of low reactivity was facilitated by use of excess Simmons-Smith reagent and distillation of ether to a halfvolume followed by heating in a stainless steel tube 182). The Simmons-Smith reaction was successfully applied to vinyl trimethylsilyl ethers to prepare, after methanolysis, cyclopropyl alcohols unobtainable by other methods 109). Here, the zinc-silver couple was used instead of the zinc-copper couple, and the quenching of the reaction mixture of the Simmons-Smith reaction was improved by using pyridine under nonaqueous conditions. 

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