Cyclopropane derivatives bonding

Whenever functional groups are connected with a C=C double bond, their reactivity is often relayed through that double bond. Analogous rules can be applied to the corresponding cyclopropane derivatives. 

The majority of preparative methods which have been used for obtaining cyclopropane derivatives involve carbene addition to an olefmic bond, if acetylenes are used in the reaction, cyclopropenes are obtained. Heteroatom-substituted or vinyl cydopropanes come from alkenyl bromides or enol acetates (A. de Meijere, 1979 E. J. Corey, 1975 B E. Wenkert, 1970 A). The carbenes needed for cyclopropane syntheses can be obtained in situ by a-elimination of hydrogen halides with strong bases (R. Kdstcr, 1971 E.J. Corey, 1975 B), by copper catalyzed decomposition of diazo compounds (E. Wenkert, 1970 A S.D. Burke, 1979 N.J. Turro, 1966), or by reductive elimination of iodine from gem-diiodides (J. Nishimura, 1969 D. Wen-disch, 1971 J.M. Denis, 1972 H.E. Simmons, 1973 C. Girard, 1974),... 

In similar reactions, (12) with carbon—carbon double bonds that are conjugated with carbonyl groups gives cyclopropane derivatives (eq. 24) (48) ... 

Section 14.13 Carbenes aie species that contain a divalent carbon that is, a caibon with only two bonds. One of the chaiacteiistic reactions of caibenes is with alkenes to give cyclopropane derivatives. 

Woodworth, based on the common reaction of addition of carbenes to double bonds to form cyclopropane derivatives (15-50). If the singlet species adds to cis-2-butene, the resulting cyclopropane should be the cis isomer since the movements of the two pairs of... 

Carbenes and substituted carbenes add to double bonds to give cyclopropane derivatives ([1 -f 2]-cycloaddition). Many derivatives of carbene (e.g., PhCH, ROCH) ° and Me2C=C, and C(CN)2, have been added to double bonds, but the reaction is most often performed with CH2 itself, with halo and dihalocarbenes, " and with carbalkoxycarbenes (generated from diazoacetic esters). Alkylcarbenes (HCR) have been added to alkenes, but more often these rearrange to give alkenes (p. 252). The carbene can be generated in any of the ways normally used (p. 249). However, most reactions in which a cyclopropane is formed by treatment of an alkene with a carbene precursor do not actually involve free carbene... 

Double-bond compounds that undergo the Michael reaction (15-21) can be converted to cyclopropane derivatives with sulfur ylids. Among the most common of these is dimethyloxosulfonium methylid (109), which is widely used to... 

Esters of a-diazoalkylphosphonic acids (95) show considerable thermal stability but react with acids, dienophiles, and triphenylphosphine to give the expected products. With olefinic compounds in the presence of copper they give cyclopropane derivatives (96), but with no such compounds present vinylphosphonic esters are formed by 1,2-hydrogen shift, or, when this route is not available, products such as (97) or (98) are formed, resulting from insertion of a carbenoid intermediate into C—C or C—H bonds. The related phosphonyl (and phosphoryl) azides (99) add to electron-rich alkynes to give 1,2,3-triazoles, from which the phosphoryl group is readily removed by hydrolysis. 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Syntheses of lactones and lactams The syntheses of sulphones, sulphoxides and cyclic sulphides... 

Not surprisingly, electron-poor systems react with chloroform, bromoform and other haloalkanes under basic conditions by Michael-type addition of the trihalomethyl anion to the C=C bond. However, a subsequent base-catalysed ring closure to give the cyclopropane derivatives frequently occurs [e.g., 6,7,26,31,39,72, 84,93,111, 113, 115, 118]. 

The DCA-sensitized irradiation of 107a for 13 hr affords, after column chromatography on silica gel, the rrans -cyclopropane derivative 108a (10%) as a 1 1 mixture of C=N bond fiZ-isomers. Similarly, irradiation of the oxime acetate 107b under these conditions for 2.5 hr affords, after chromatography, the rrans -cyclopropane derivative 108b (12%). These results show that the novel 1-ADPM rearrangement promoted by electron-transfer sensitization can be extended to other C—double-bond derivatives. 

When l,4-dihydronaphthalen-l,4-imine (2) was first obtained via the hydrobromide (113), it was shown to react with phenyl azide to give an adduct (127). The analogous phenyl azide adduct (128) from compound 103 has been better characterized. Naphthalen-l,4-imines also add diazomethane across the 2,3-double bond, forming pyrazolines, e.g., 104 -> 129, two of which have been photolyzed to give the corresponding cyclopropane derivatives (130) with extrusion of nitrogen. ... 

Reduction of unsaturated aromatic aldehydes to unsaturated hydrocarbons poses a serious problem, especially if the double bond is conjugated with the benzene ring or the carbonyl or both. In Clemmensen reduction the a,)8-unsaturated double bond is usually reduced [160], and in Wolff-Kizhner reduction a cyclopropane derivative may be formed as a result of decomposition of pyrazolines formed by intramolecular addition of the intermediate hydrazones across the double bonds [280]. The only way of converting unsaturated aromatic aldehydes to unsaturated hydrocarbons is the reaction of... 

Cycloproparenes may be prepared by formation of one of the lateral cyclopropane o-bonds either via biradical closing, or via 1/3/elimination. The first reported synthesis of a benzocyclopropene derivative (see Section 1)" is an application of the former of these approaches. Upon irradiation, 3//-pyrazoles 70 loose Nj, and the intermediate biradical 71 cyclizes to 72. There is evidence that the intermediate biradical is in the triplet state, but an alternative interpretation in favor of an excited singlet state has also been presented. A variety of 1,1-disub-stituted benzocyclopropenes has been synthesized by the 3ff-indazole route, which is however limited. Cycloproparenes lacking substituents at Cl are not accessible in this way, because the required indazoles occur in the IH tautomeric form 73. 

Artemisyl, Santolinyl, Lavandulyl, and Chrysanthemyl Derivatives.— The presence of (41) in lavender oil has been reported earlier. Poulter has published the full details of his work (Vol. 5, p. 14) on synthetic and stereochemical aspects of chrysanthemyl ester and alkoxypyridinium salt solvolyses (Vol. 3, pp. 20—22) and discussed its biosynthetic implications. Over 98% of the solvolysis products are now reported to be artemisyl derivatives which are formed from the primary cyclopropylcarbinyl ion (93) which results from predominant (86%) ionization of the antiperiplanar conformation of (21)-)V-methyl-4-pyridinium iodide the tail-to-tail product (96 0.01%) may then result from the suprafacial migration of the cyclopropane ring bond as shown stereochemically in Scheme 3. This is consistent with earlier work (Vol. 7, p. 20, ref, 214) reporting the efficient rearrangement of the cyclobutyl cation (94) to (96) and its allylic isomer, via the tertiary cyclopropylcarbinyl cation (95). ... 

A large number of cyclopropanated derivatives of Cgo in which the bridging atom is an electron rich transition metal (see Fig. 16) such as Pt, Pd, Ni, Ir, W, Mo, and Rh has been reported. Their electrochemical properties have been reviewed [83, 141, 142] and, in general, reductions are Cgo centered and negatively shifted with respect to those of pure Cgo, while oxidations are metal centered. In most cases, however, the first reduction is accompanied by breakage of the carbon-metal bonds and recovery of the pristine [60] fullerene. In multiadduct derivatives, the breakage occurs in a stepwise manner. 

The structures of bicyclic and polycyclic small-ring compounds have attracted some interest. The relationship between the C-C-H bond angles at the bridgehead of bicyclo[1.1.0]butane (2) and the angle between its cyclopropane rings has been studied.31 Bicyclobutane and most other cyclopropane derivatives have bonds that are formed from orbitals that are bent in the same direction. However, with some mm -fused bicyclic compounds containing a cyclopropane... 

Another example of a remarkably distorted cyclopropane derivative is tricyclo[2.1.0.01,3]pen-tane (5), which has a C-C-C bond angle of 164.5°. Not surprisingly, it is a relatively unstable compound that can only be observed by NMR at — 55°C.36... 

Cyclopropane derivatives, including spiropentanc, have proven to be virtually inert towards carbenes,1 For this reason, no literature report that describes cyclobutane synthesis from a C3 and a Cj building block by ring enlargement of cyclopropanes exists. However, due to the partial p character, as well as the increasing reactivity caused by its strain, the central bond of bicyclo[1.1.0]butane (l)2 has been found to react with carbenes.1 Photolysis of diazomethane in the presence of bicyclo[1.1.0]butane (1) at — 50 C provides a mixture of several compounds. The major fraction of the material (80%) was analyzed by means of NMR spectrometry and found to consist of penta-1,4-diene (2, 21%) and bicyclo[l.l.l]pentane (3, 1%), plus several other known compounds as well as some unidentified products.3 The mechanistic pathway for the formation of bicyclo[l.l.l]pentane (3) has not been addressed in detail, but it is believed that a diradical intermediate is involved, as shown below.3... 

---