A Convenient Synthesis of Dimethyl and Diethyl Diazomalonate

High-Yield Double Cyclopropanation of Benzene

“…Fraction A was identified as a mixture of 7 , 8 , and 9 (eq 3), based on comparison with reported 1 H NMR spectra. − Compounds 7 and 8 have been shown to be in rapid equilibrium, with K eq = 0.30 at the temperature of refluxing benzene and K eq = 0.31 at room temperature . The ratio of [ 7 + 8 ] to 9 depended somewhat on the duration of reflux and was in the range [ 7 + 8 ]/ 9 = 2.3−3.0 for reflux times of 4−8 h. These products are unremarkable, inasmuch as they have been reported before for thermal and photochemical cases of the Büchner reaction of DDM with benzene …”

Reactions Involving Hetero Atoms

“…Attack of an excited acetone molecule on ground-state diazomethane was assumed for the UV region < 3200 Â. With light of wavelength > 3200 Â, diazomethane was believed to be the absorbing species, Under these conditions, the major products were butan-2-one, 2,2-dimethyloxirane, 2-methoxypropene, and 2,2,4,4-tetramethyl-l,3-dioxolane [73]. Whereas butan-2-one is most probably a product of direct C-H insertion, the remaining compounds may be derived from the dipolar intermediate [72] which arises by attack of CH 2 on the carbonyl oxygen.…”

Dehydrogenation of Hydrazones

“…Examples of the selective conversion of only one carbonyl group into 233 the diazo functionality are isatine (2), alloxane (3) and diethyl mesoxalate (4). Usually no problems are encountered for aldehydes and monoketones, or for di-and triketones where one C=0 group is more reactive than the others.…”