New bis- and trishomobenzene derivatives

Abstract

Sir :Considering the amount of work which has been reported on norcaradiene-cycloheptatriene equilibria in general,' and specifically on the structures of Buchner's esters, we were surprised to find two new adducts of carbomethoxycarbene and benzene, i.e., the 2 : 1 and 3 : l adducts, 1 and 2. We are prompted to report 1 2 their preparation and stereochemistry now by recent reports of other bis-and trishomobenzene derivatives.3The synthetic procedure consists of slowly adding (24 hr) a solution of 20 g of methyl diazoacetate in 50 ml of benzene to 50 ml of refluxing benzene containing 0.5-1.0 g of finely powdered copper-bronze. After evaporation under vacuum of the volatile components of the reaction mixture (benzene, dimethyl fumarate, dimethyl maleate, and methyl cycloheptatriene-7-carboxylate), the 2: 1 and 3 : 1 adducts were isolated by column chromatography of the residual oil (Silica gel,The 2 : 1 adduct, dimethyl tricyclo[5.1 .0.02b4]oct-5ene-3,8-dicarboxylate (l), mp 130-132", was isolated in 3% yield and was shown to have the structure and stereochemistry indicated by the following observat i o n~.~ The nmr spectrum (CDCI,) showed two olefinic protons as an apparent triplet at 6 5.70, six methoxy protons as a singlet at 3.65, and a complicated multiplet of six protons at 1.5-2.2. The proton ratios indicate a tricyclic skeleton, and the magnetic equivalence of the olefinic protons and the methoxy protons suggested a symmetrically substituted (exo,exo-or endo,endo-) tricyclo[5.1 .0.02~4]oct-5-ene. Double irradiation at 6 1.6 caused the olefinic triplet to collapse to a singlet, and, conversely, irradiation at 5.7 simplified the highfield signals allowing analysis of the region as two identical ABC systems: Ha, 6 2.12; Hb, 1.78; H,, 1.63; the small values of the coupling constants Jab and Jbc,6CC14-CHC13). J a b = 3.9 HZ, Jac = 8.6 HZ, J b c = 4.0 H z .~ Based on , J. Amer. Chem. Soc., 93, 3837 (1971).(4) Satisfactory elemental analyses and mass spectral molecular weights have been obtained for all new compounds reported. The nmr spectra reported were recorded on a Varian A-60, (5) Parameters refined by L A O C N~ spectral analysis program of A. A.

High-Yield Double Cyclopropanation of Benzene

“…The low yield of double-cyclopropanation product 10 obtained with Rh 2 (O 2 CCF 3 ) 4 is comparable to other carbenoid reactions with aromatics, in which double-cyclopropanation is almost never found. Despite the long history of the Büchner reaction, double cyclopropanation has been reported in only the following few instances of which we are aware: (a) the copper−bronze-catalyzed reaction of methyl diazoacetate with benzene, which gave 11 in 3% yield; (b) the solvent-free thermal reaction of naphthalene with excess DDM, which gave 12 in 5−15% yield; (c) the thermal addition of ethyl diazoacetate to naphthalene and two symmetrical dimethylnaphthalenes, which gave 13a and 13b in 14−17% yield ( 13a / 13b = 2.6), 13c in 11% yield, and 13d in 19% yield; (d) the CuCl-catalyzed reaction of diazomethane with N -carbomethoxypyrrole, which gave 14a in 12% yield and a trace of 14b , and the CuBr-catalyzed reaction of ethyl diazoacetate with N -carbomethoxypyrrole, which gave 14c in 5% yield; and (e) the Rh 2 (OAc) 4 -catalyzed reaction of diethyl ( Z )-2-methoxy-4-diazo-2-pentenedioate with N -carbomethoxypyrrole, which gave 14d in 33% yield . The formation of diadduct 15 from CuSO 4 -catalyzed addition of methyl diazoacetate to anthracene has been mentioned, but a yield was not given…”

Seven-membered conjugated carbo- and heterocyclic compounds and their homoconjugated analogs and metal complexes. Synthesis, biosynthesis, structure, and reactivity

“…The long tried483 intramolecular "dimerization" of aketo carbenes has recently been reported.4813 In the case of 1,7-bisdiazo-4-chloroheptane-2,6-dione (64), obtained from glutaconic acid (63) in three steps, decomposition under high dilution conditions with copper acetylacetonate led to 6-chlorocyclohept-2-ene-1,4-dione (65) which, either spontaneously in vacuo or under the influence of triethylamine, was dehydrochlorinated and enolized to 4hydroxytropone (66) in ca. 27% overall yield.4813 g cojH co2h 63 3.…”

“…Recently it has been discovered that benzene, on treatment with methyl diazoacetate in the presence of copper-bronze, produces bis (81) and tris adducts (82) only. 65 The causes of this unusual behavior are not clear, though it is possible that the norcaradiene-cycloheptatriene equilibrium is strongly affected by the heterogeneous catalyst surface. 65 Other insertion reactions of dlazomethane occur with o-benzoqulnol acetate (to give tropone and 2,3,5-trialkyltropones),66 and with some p-benzoqulnones67 (to give 2,6-dl-ferf-butyl-4-hydroxytropone67a or 2-methoxy-4-hydroxy-5-acetyl-6-alkyltropones67b).…”

syn‐Tricyclo[5.1.0.02,4]oct‐5‐en‐3,8‐dicarbonsäureester

“…Ether bei 25°C losen (hieraus nach Veresterung und Chroma-tographie0.8g (7) und 1.Og ( 4 ) ) . Der Rest ergibt nach Diazomethanbehandlung in Methanol/Ether und Chromatographie an S i 0 2 rnit CH2CI2 8.7g ( 4 ) .…”