Diazoethane

The pyrolysis of diazoethane involves the formation of ethylidine, detected by the mirror technique . The photolytic decomposition also proceeds via ethylidine and has been investigated by several workers in order to determine the chemical reactivity of ethylidine. In the long wavelength photolysis (4358 ethylidine is fairly unreactive and isomerizes readily to vibra- 

---

The only synthesis which corresponds with this description formally, though not mechanistically, resulted in formation of (385) from a side reaction in the attempted esterification of the pyridinone acid (383) with diazoethane, via ring expansion of the putative intermediate (384) (76CPB1870). 

Any heterocycle containing the OCH=CH moiety can in principle extrude the superfluous fragment and form oxirene, as illustrated for a five-membered ring in Scheme 105. Probably the most propitious AB fragment would be nitrogen, but the required 1,2,3-oxadiazole (123) is unknown (see Chapter 4.21), probably because of ready valence tautomerization to diazoethanal (Scheme 106) (this approach has been spectacularly successful with the sulfur analogue of (2) (8UA486)). The use of (123) as an oxirene precursor is thus closely linked to the important diazo ketone decompositions discussed in Section 5.05.6.3.4(f). 

The lifetime of the diazomethane adduct is not known, but it must be of sufficient length that carbon can compete with nitrogen in participation as a nitrogen molecule leaves (24,109). The reaction of 66 with diazoethane yields 72, the normal adduct, and 73, the product from ring expansion. The structure of 73 was determined by hydrolysis to 2-methylcyclo-heptanone. In a similar reaction 74 yields 67 directly without isolation of 66. A similar ring expansion has been observed for cyclooctanone derivatives (16). 

Under similar conditions, the interaction between diacetylene and diazoethane (68CB3700) gives rise to 5-ethynyl-3-methyl-l//-pyrazole in 34% yield (Scheme 11). 

The reaction between acyl halides and diazomethane is of wide scope and is the best way to prepare diazo ketones. Diazomethane must be present in excess or the HX produced will react with the diazo ketone (10-74). This reaction is the first step of the Amdt-Eistert synthesis (18-8). Diazo ketones can also be prepared directly from a carboxylic acid and diazomethane or diazoethane in the presence of dicyclohexyl-carbodiimide. ... 

Urine Acidify and heat to hydrolyze add NaOH extract with anhydrous ethyl ether derivatize with diazoethane concentrate add hexane concentrate and cleanup on silica gel elute with benzene-hexane (PNP) GC/ECD 20 pg/L (20 ppb) 85-98 Shafiketal. 1973b... 

The scope of the multi-residue method is extended permanently by testing and then including further active substances that can be determined by GC. Acidic analytes (such as phenoxyacetic acids or RCOOH metabolites) are included into the homogeneous partitioning by acidifying the raw extracts to a pH below the pKs value of the carboxylic acids. To include these analytes in the GC determination scheme they have to be derivatized with diazomethane, diazoethane, trimethylsilyldiazomethane, acidic esterification or benzylation, or by silanizing the COOH moiety. 

Gas-phase photolysis of diazoethane results in mixtures of ethylene, acetylene, and cis- and frans-2-butene. A mechanism involving the initial formation of ethylidene followed by formation of activated ethylene [which is collisionally deactivated or decomposes to produce acetylene and hydrogen— Eqs. (11.26(b,c,d)] or alternate attack on diazoethane to produce 2-butene [Eq. 11.26(e)] is proposed ... 

In the presence of propene, photolysis of diazoethane yields cis and trans isomers of 1,2-dimethylcyclopropane ... 

Reactions with Other Substrate Complexes. The ruthenium analog of 45, coordinatively unsaturated RuCl(NO)(PPh3)2, also yields methylene and ethylidene complexes on treatment with diazomethane and diazoethane (39,85). 

As follows from the comparison of the rates of oxidation and destruction of linear and branched polyalkenes, the branched form possesses more susceptible tertiary C—H bonds and oxidizes more rapidly (but degrade more slowly) than the linear form. This was observed for PS, PE, PP, polyfrt-isopropyl styrene), polymethylene, and polymers produced by the decomposition of diazomethane-diazoethane and diazomethane-diazobutane mixtures [125], The number of cleavages per oxygen molecule consumed at 403 K amounts to 0.25 for PE and to 0.04 for PP. 

Diazomethane or diazoethane are used to prepare analogous ethyllead compounds411 ... 

Alkylation with Diazo Compounds Diazomethane or diazoethane are commonly used as diazo compounds. The reactions of these alkylating agents proceed smoothly only with AN containing electron-withdrawing groups (EWG) adjacent to the a-C atom (4-6) (Scheme 3.3). 

The method is of general applicability7 for the synthesis of olefins. Other sulfonyl chlorides, RCH2SO2CI, have been used where R = H, C2H5, CeHs, and C6H5CH2 other diazoalkanes that have been used are diazoethane and l-diazo-2-methyl-propane. In all cases the olefins form without double-bond migration. 

The diazomethane methodology has previously been applied by several other groups to expand cyclobutanones. For example, in Fleming s loganin synthesis, 53,54) when the cyclobutanone (151) was allowed to react with diazoethane, (152) was isolated as a mixture of stereoisomers. Removal of the chlorine atom and equilibration of the methyl group with NaOMe converted (152) to the ketone (153) 53,54). 

Diazoethane, reaction with sulfonyl chlorides and triethylamine, 48 108... 

Treatment of thiobenzophenone with 1 equivalent of diazoethane in CH2CI2 at — 78°C produced 5-methyl-2,2-diphenylthiadiazoline (143) which actually crystallized from a concentrated solution however, when the crystals were warmed to room temperature, they exploded. In a THE solution at — 45°C (143) decomposed with nitrogen evolution following first-order kinetics with a half-life of 18 minutes. The product was 2-methyl-1,1-diphenylthirane (144) which slowly lost sulfur to yield 1,1-diphenylpropene (145) <83H(20)2363>. 

Etbyl-3-nitrobenzoate, monoclinic prisms, mp 47°, bp 296° It may be prepd by saturating an ale soln of the acid with. HCl gas from the acid salt of 3 nitrobenziminoethylether from the 3-nitro acid and diazoethane and from the >nitro benz in bulling abs ale and HCl gas Ref Beil 9, 378, (151), (154) [248] Etbyl 4-nitrobenzoate, pi tits (from ale), mp 57°. It may.be prepd from the acid in ale in the presence of HCl, from the methyl ester and excess ale in the presence of KOCH3 Ref Beil 9, 390 [258]... 

Dihydrobenzoxocinone (149) is produced by decomposition of the pyrazoline (148), from the reaction of 3-acetylcoumarin with excess diazoethane (74JCS(P1)66). The boat-like conformation (150) is assigned to the eight-membered ring. 

---