Ethyl diazoacetate, reduction

Initial one-electron oxidation of the diazo compound by Ag(I), Hg(II) or Cu(II) acetates may also be responsible for the formation of Ph2C(OAc)—C(OAc)Ph2 from diazodiphenylmethane and of EtOOCCH(OAc)—CH(OAc)COOEt from ethyl diazoacetate in DMF/H20 417). Direct evidence for reduction of Cu(II) triflate to the Cu(I) salt by alkyl diazoacetates has been furnished by the disappearance of the... 

Other oxazoline containing ligands have been reported for the copper-catalyzed cyclopropanation reaction. These are outlined in Scheme 5 where the reaction of ethyl diazoacetate and styrene is compared. Conditions are more or less standard (halogenated solvent, 0°C to ambient temperature, CuOTf without reduction). For more information on these ligands, the reader is referred to the primary publications (49-54). 

The relative stereochemistry of the substituents attached to the cyclopropane ring of presqualene alcohol received further confirmation by a synthesis of the triacetate (13), obtainable from (1) by ozonolysis, reduction, and acetylation. Treatment of 3-methyl-truns-hex-2-ene-l,6-diacetate (14) with ethyl diazoacetate in the presence of copper powder gave two isomers (15) and (16) whose stereochemistry was assigned by n.m.r. The triacetate derived from synthetic (15) by reduction and acetylation was identical in all respects with the triacetate (13) from natural presqualene alcohol. Presqualene alcohol has a c.d. curve similar to, but of opposite sign to, that of (li ,2i )-trans-chrysanthemyl alcohol (17). The mechanism for the stereospecific biosynthesis of squalene from farnesol via presqualene alcohol has received detailed comment. ... 

For purposes of classification the 4-aminopyrazoles are considered to be 4-imino-2-pyrazolines and analogs of 2-pyrazolin-4-ones. These compounds are listed in Table XL. Such compounds can be prepared by direct cyclization using ethyl diazoacetate and ethyl cyanoacetate.92 This is the same as eq. 243, except that the malonic ester is replaced by ethyl cyanoacetate. Purines can be hydrolyzed to 4-imino-2-pyrazolines by using strong acid.1210 1846 By far the most frequently used preparation is reduction of appropriately substituted pyrazoles, such as 4-nitro,368,812,819,1015,1019,1049 4-nitroso1165 or 4-aryl-azo.671 974,995 The hydrolysis of the carbethoxy 4-imino-2-pyrazolines derived from ethyl cyanoacetate and ethyl diazoacetate forms 4-imino-2-pyrazolin-3-carboxylic acid which is readily decarboxylated to the parent compound.92... 

S,S)-2,3-Butanediol (see Section 4.1.2. for access to this compound) was the starting material for the synthesis of (S,S)-2,3-dimethyl-18-ciown-6 (6) which has been used as a chiral catalyst in the enantioselective Michael addition reaction (Sections D.1.5.2.1. and D.I.5.2.4.). Chain elongation of the diol by reaction with ethyl diazoacetate and lithium aluminum hydride reduction, followed by cyclization with triethyleneglycol ditosylate, gives the crown ether 610. 

Ethyl diazophenylacetate is reduced to phenylacetate in aqueous dioxane at pH 7 (Jugelt et al., 1972). The authors reported that dinitrogen is formed, clearly indicating that the mechanism of this reduction is different from that of 2-diazo-l-phenylethan-l-one. Under aprotic conditions (sulfolane), ethyl diazoacetate, but... 

The redox potentials of one-electron oxidation and reduction of aliphatic diazo compounds are relatively small. A table published by Bethell and Parker (1988, p. 400) contains seven corrected oxidation potentials including those of diazomethane, ethyl diazoacetate, diazodiphenylmethane, 9-diazofluorene, and of compounds 9.56 and 9.59. They were obtained by various authors using a rotating platinum disk electrode in acetonitrile and cover the range E i/2(ox) 0.77-2.10 V. The reduction potentials E i/2(red) -1.12 to —1.71 V for four compounds (diethyl diazomalonate, diazodiphenylmethane, 9.56 and 9-diazofluorene) are not strictly comparable because the measurement conditions (cyclic voltammetry) were not exactly the same. 

More epoxides (1) with juvenile hormone activity (Vol. 2, p. 7) have been made by epoxidizing the Wittig products of citronellal (2), and some of these substances also increase silk production.Reduction of the double bond sometimes increases the activity against Oncopeltus fasciatus. Insecticidal activity is also reported for certain terpenoid cyclopropanes [e.g. (3), made from limonene and ethyl diazoacetate] and for isobornyl thiocyanoethyl ether (made from cam-phene and ethylene chlorohydrin followed by treatment with potassium thiocyanate). The insect-repelling activity shown by thujic acid amides (4) is... 

Aziridines are commonly prepared from imine precursors. Carbene addition to the C=N bond is illustrated by the formation of aziridine 127 from imine 126. ° Difluorocarbene, generated from HFPO (1), also adds to imines such as 128 to give the highly fluorinated aziridine 129. In the presence of Lewis acids, diazo compounds react with imines to produce aziridines. Ethyl diazoacetate and imine 130 gave aziridine 131 in 93% yield, with a cis/trans ratio of 95 5. Chiral diazo compound 132 reacted with the aldimine precursor 133 to afford aziridine 134 in 81 % yield.The reaction displayed both high cis selectivity (>95 5) and excellent diasteroselectivity (94% de). Reductive removal of the chiral auxiliary gave the optically active hydroxymethylaziridine 135. 

The total synthesis started with a Birch reduction of p-methoxytoluene (382) to obtain the dihydro compound 383, which was treated with p-toluenesulfonic acid to obtain acetal 384. CyclopropanatiOTi with ethyl diazoacetate and transaceta-lization led to compound 385, which reacted to the unsaturated keto ester 386 on treatment with base. In the next step, the keto ester 386 was methylated with methylmagnesium chloride, and it reacted selectively at the 2-positon to yield 387. Lactonization with further methylation with methyl iodide afforded homo-lactone 389, which reacted with lithium salt 390 to alkyne 391 and was reduced with sodium borohydride to diol 392. Partial reductiOTi of the triple bond to the double bond was obtained with sodium in ammonia and further treatment with acid led to hydrolysis of the acetal, which subsequently cychzed to 394 (Scheme 8.1). 

Craig and coworkers have reported stereocontrolled polyol synthesis via C-H insertion reactions of silicon-tethered diazoacetates.7 Menthol was treated with diisopropylsilyl bis(trifiuoro-methanesulfonate) and the product was condensed with ethyl diazoacetate to provide the precursor 43 to the C-H insertion reaction (eq 10). The rhodium(II) octanoate-catalyzed decomposition of the diazoacetate 43 gave siloxane 44 as a single stereoisomer. Reduction of the ester, followed by oxidative cleavage of the C-Si bond, gave the desired polyol 46 in 30% yield, along with the elim-... 

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