Methyl cyclopropane

Cyclopropan 1 -Methyl- 1-phenylazo-E19a, 775 [aus (3-Hydrazono-alkyl)-Sn-Verb.]... 

CYCLOPROPANES Methyl diazo propionate. Copper(l)oxide-(-Butyl isonitrile. CYCLOPROPENONE Tri-fi-butyltin hydride. 

Similar reactions were observed when 1 -phenyldiazoethane was allowed to react with methyl ( )-2-cyano-3-(4-substituted phenyl)acrylates in dichloromethane at — 5 to 0 °C. The expected cyclopropanes, methyl 1 -cyano-3-methyl-3-phenyl-2-(4-substituted phenyl)cyclopropanecarb-oxylates 2, were formed in moderate to low yields. In addition, significant amounts of methyl 2-cyano-4-phenyl-4-(4-substituted phenyl)pent-2-enoates 3, formed by rearrangement from postulated dihydropyrazole intermediates, and methyl 4-cyano-3-methyl-3-phenyl-5-(l-phenyT l-(4-substituted phenyl)ethyl]-4,5-dihydro-3f/-pyrazole-4-carboxylates4, formed by 1-phenyldiazoethane attack on 3, were obtained. ... 

BUTENE. As shown in Figure 38, a group attached to C-1 can migrate from position 1 to 3 (1,3 shift) to produce an isomer. If it is a methyl group, we recover a 1-butene. If it is a hydrogen atom, 2-butene is obtained. A third possible product is the cyclopropane derivative. The photochemical rearrangement of 1-butene was studied extensively both experimentally [88]... 

Ethyl-5-methyl (3R, 5R) and (3R, 55) derivatives Elucidation of the stereochemistry of the pyrazoline-> cyclopropane reaction 77JA2740... 

The stabilization of chloromethoxycarbene (234) was intensively studied. It is formed from diazirine (233) in a first order reaction with fi/2 = 34h at 20 C. It reacts either as a nucleophile, adding to electron poor alkenes like acrylonitrile with cyclopropanation, or as an electrophile, giving diphenylcyclopropenone with the electron rich diphenylacetylene. In the absence of reaction partners (234) decomposes to carbon monoxide and methyl chloride (78TL1931, 1935). 

In laser-impulse experiments with chlorophenyldiazirine the carbene could be observed by UV spectroscopy. On addition of defined amounts of alkene the rate of cyclopropanation was measured directly. The rate constants with various alkenes were (lO moF s ) 1-hexene, 1.3 ( )-2-pentene, 34 2-methyl-2-butene, 77 2,3-dimethyl-2-butene, 130 (80JA7576>. 

Cyclopent-2-en-l-one, 2-hydroxy-3-methyl-synthesis, 3, 693 Cyclopentenone, 4-methoxy-formation, 1, 423 Cyclopenthiazide as diuretic, 1, 174 Cyclopent[2,3-d]isoxazol-4-one structure, 6, 975 Cyclophane conformation, 2, 115 photoelectron spectroscopy, 2, 140 [2,2]Cyclophane conformation, 2, 115 Cyclophanes nomenclature, 1, 27 Cyclophosphamide as pharmaceutical, 1, 157 reviews, 1, 496 Cyclopiloselloidin synthesis, 3, 743 Cyclopolymerization heterocycle-forming, 1, 292-293 6H-Cyclopropa[5a,6a]pyrazolo[l,5-a]pyrimidine pyrazoles from, 5, 285 Cydopropabenzopyran synthesis, 3, 700 Cyclopropachromenes synthesis, 3, 671 Cyclopropa[c]dnnolines synthesis, 7, 597 Cyclopropanation by carbenes... 

C3H6 CYCLOPROPANE 51.643 1.6873E-01 2.4956E-05 104.39 146 C4H8 2-METHYL- PROPENE -18.295 2.4609E-01 3.0860E-05 58.07... 

The additional coupling (9.8 Hz) of the cyclopropane proton A at <5// = 1.60 is the result of a vicinal H atom in the side-chain. This contains a methyl group B, a vinyl group C and an additional substituted ethenyl group D, as may be seen from the one dimensional H and C NMR spectra and from the CH COSY diagram. 

In decoupling the methyl protons, the NOE difference spectrum shows a nuclear Overhauser enhancement on the cyclopropane proton at = 1.60 and on the terminal vinyl proton with trans coupling at <5// = 5.05 and, because of the geminal coupling, a negative NOE on the other terminal proton at Sh= 4.87. This confirms the trans configuration G. In the cis isomer H no NOE would be expected for the cyclopropane proton, but one would be expected for the alkenyl-// in the a-position indicated by arrows in H. 

These results indicate an energy profile for the 3-methyl-2-butyl cation to 2-methyl-2-butyl cation rearrangement in which the open secondary cations are transition states, rather than intermediates, with the secondary cations represented as methyl-bridged species (comer-protonated cyclopropanes) (Fig. 5.10). 

Pyrolysis at 190° of the resulting diastereomeric A -pyrazolines (8) and (11) leads to elimination of nitrogen and formation of the cis- and tmns-cydo-propanecarboxylates (9) and (12), respectively. Thermal decomposition of the A -pyrazoline (13) affords methyl tiglate (14) in addition to the cyclopropane derivative (15) in a ratio 2 1, while A -pyrazolines such as (3) give only 0L,[i- or, y-unsaturated esters, and no cyclopropane derivatives. 

High vacuum pyrolysis, heating in organic bases, contact with acidic adsorbents and reaction at room temperature with perchloric acid or boron trifluoride etherate cleaves the pyrazoline to give a 45-60% yield of the cyclopropane derivative (13) as well as 9 % of the unsaturated methyl compound (14). ° ... 

In A -3-keto-5jS-H steroids (7) the attack of the Corey reagent occurs towards the ) -face forming 1 j8,2j6-methylene-5) -H compounds (8). The / -configuration of the cyclopropane ring was established by conversion of (8) into the corresponding IjS-methyl compound. ... 

The addition of nucleophiles to cyclic fluoroolefins has been reviewed by Park et al. [2 ]. The reaction with alcohols proceeds by addition-elimination to yield the cyclic vinylic ether, as illustrated by tlie reaction of l,2-dichloro-3,3-di-fluorocyclopropene Further reaction results in cyclopropane ring opening at the bond opposite the difluoromethylene carbon to give preferentially the methyl and ortho esters of (Z)-3-chloro-2-fluoroacrylic acid and a small amount of dimethyl malonate [29] (equation 8). 

In addition to unsaturated fatty acids, several other modified fatty acids are found in nature. Microorganisms, for example, often contain branched-chain fatty acids, such as tuberculostearic acid (Figure 8.2). When these fatty acids are incorporated in membranes, the methyl group constitutes a local structural perturbation in a manner similar to the double bonds in unsaturated fatty acids (see Chapter 9). Some bacteria also synthesize fatty acids containing cyclic structures such as cyclopropane, cyclopropene, and even cyclopentane rings. 

In Corey and Chaykovsky s initial investigation, a cyclic ylide 79 was observed from the reaction of ethyl cinnamate with ylide 1 in addition to 32% of cyclopropane 53. In a similar fashion, an intermolecular cycloaddition between 2-acyl-3,3-bis(methylthio)acrylnitrile 80 and 1 furnished 1-methylthiabenzene 1-oxide 81. Similar cases are found in transformations of ynone 82 to 1-arylthiabenzene 1-oxide 83 and N-cyanoimidate 84 to adduct ylide 85, which was subsequently transformed to 1-methyl-lX -4-thiazin-l-oxide 86. ... 

The methylethylcarbene which is formed thermally from methyl-ethyldiazirine at 160°C gives the same products as that from butanone p-toluenesulfonylhydrazone and bases in aprotic solvents." However, photolysis of the same diazirine gives a different mixture of C4H8 hydrocarbons. Considerable amounts of 1-butene are formed, the trans-butene content is reduced by half, and the amount of methyl cyclopropane increased fivefold. ... 

---