Diazomethyl acetate

On the other hand, with 1,2-disubstituted or certain trisubsti-tuted olefins, the chiral ligand also influences the trans/cis selectivity. For example, treatment of a glucose-derived enol ether with diazomethyl acetate in the presence of Cu[(5, 5)-/-Bu-box] (OTf) complex affords the cyclopropanation product with an excel-... 

It was later demonstrated that decomposition of a dialkyl ruthenium(IV) porphyrin also yields the carbene species (TPP)Ru(CHCH3) due to a-abstrac-tion [127]. More recently [128], it was reported that addition of ethyl diazomethyl acetate to the 14 electron species, (TMP)Ru [129], also affords (TMP)Ru(CHC02CH2CH3) in a more classical route (Eq. 17). 

The first X-ray structure of a ruthenium porphyrin carbene complex was reported by Simonneaux and coworkers (Fig. 1) [133]. To stabilize the ruthenium carbene complex, ethyl diazomalonate was used instead of ethyl diazomethyl acetate, as was previously reported in the bis(oxazolinyl)pyridine (pybox) series [134]. The presence of this complex as an intermediate in cy-clopropanation was also discussed in relation with stoichiometric transfer to alkenes (vide infra) [135]. 

Intramolecular oxonium ylide formation is assumed to initialize the copper-catalyzed transformation of a, (3-epoxy diazomethyl ketones 341 to olefins 342 in the presence of an alcohol 333 . The reaction may be described as an intramolecular oxygen transfer from the epoxide ring to the carbenoid carbon atom, yielding a p,y-unsaturated a-ketoaldehyde which is then acetalized. A detailed reaction mechanism has been proposed. In some cases, the oxonium-ylide pathway gives rise to additional products when the reaction is catalyzed by copper powder. If, on the other hand, diazoketones of type 341 are heated in the presence of olefins (e.g. styrene, cyclohexene, cyclopen-tene, but not isopropenyl acetate or 2,3-dimethyl-2-butene) and palladium(II) acetate, intermolecular cyclopropanation rather than oxonium ylide derived chemistry takes place 334 ). 

Reaction of diazomethyl ketone with ketene acetals to form 2,2-di-alkoxy-l,2-dihydropyrans [178]. 

ALKYL SELENOCYANATES Triphenyl-phosphine-Diethyl azodicarboxylate. ALKYNES Acetic anhydride-Pyridine. Dimethyl) diazomethyl)phosphonate. OrganoUthium reagents. 

Compound (8), under Vilsmeier formylation and nitration (nitric acid-acetic anhydride) conditions, proceeded as might have been expected for electrophilic substitution reactions to give the 1-substituted products (142) and (143). Reduction of (143) gave predominantly the imidazopyridine (144) with a small amount of the tetrahydro derivative (145) (81JCS(P1)78). Heating (8) in D2O led to the 1-deutero derivative (78HCA1755) via deuter-ation-deprotonation or via the tautomeric 2-(diazomethyl)pyridine tautomer of (8). 

Treatment of an acetylated diazomethyl ketose with acetic acid and a catalytic amount of cupric acetate results in replacement of the diazo group by an acetoxy group, and deacetylation then furnishes the required ketose. Since keto acetals are very sensitive to alkali, this final saponification is achieved using barium hydroxide at 0°. 

Intramolecular functionalisation of the isopropyl group of dehydroabietic acid has been achieved by the cyclisation of 12-carboxy-group to form a y-lactone (73) using lead tetra-acetate as the oxidant. Thermolysis of the 12-diazomethyl ketone also leads to cyclisation. Direct replacement of the isopropyl group by a nitro-group occurs in the nitration of methyl 12-acetylabieta-8,l 1,13-trien-18-oate. The 13-nitro-compound (74) was converted through the amine to... 

The third procedure for the synthesis of phosphorylated diazoalkyl compounds is that of diazotization of the correspondingly substituted amino compounds, As a result of the ready availability of dimethyl and diethyl (aminomethyl)phosphonates, these form the most convenient starting materials for conversion into the dialkyl (diazomethyl)phospho-nate by the use of NaN02-acid . Latterly, the customary reagent combination has been that of propyl nitrite in acetic acid, and successful conversions have been described for 16 (Z = COOR CONHR and CN ). In the case of the last substrates, the diazo transfer procedure is said to be unsuitable, because of extensive side reactions which lead to phosphorylated 1,2,3-triazoles. Most reports have been concerned with the preparation of 1 -diazoalkyl compounds, and the syntheses of compounds in which the diazo group is sited elsewhere on the carbon skeleton are very rare ... 

There are few examples of this variation in the literature. The variation relies on the alkylation of thiolactams (in replacement of cyclohexanones) by the Michael addition of diazomethyl vinyl ketone (in replacement of methyl vinyl ketones) followed by ring closure using rhodium(II) acetate mediated diazomethane insertion. The diazomethyl entity can also be added after the Michael addition step. The reaction affords six-membered rings with... 

Transition metal-catalyzed Buchner reactions of arene substrates proceed via electrophilic carbenoids. In addition to cyclopropanation of the arene double bond, these a-diazoketones possessing an aromatic ring can also participate in C-H insertion reactions. As shown in the decomposition of diazomethyl ketone 53, the benzylic C-H insertion product 56 is obtained as a minor product (vide supra). The rhodium(II) acetate-catalyzed reaction of diazoketone 71 also affords cycloheptatriene derivative 73 along with the benzylic C-H insertion product, y-lactam 72, in a ratio of 1 2. Treatment of 71 with the more electron-rich rhodium(II) caprolactamate [Rh2(Cap)4] favors more C-H insertion, but the cycloaddition pathway is still significant the ratio of 73 to 72 is 1 3.5. 

Dimethyltetrahydrofuran-3-one (175) has been synthesized in several ways (Scheme 6). The 3-ol is oxidized to the 3-one (175) by chromium trioxide in pyridine but is cleaved by lead tetra-acetate in benzene. Hydrochloric acid catalyses cyclization of 2-(benzyloxy)ethyl diazomethyl ketone (176) to (175), and hydrolysis and decarboxylation of the / -keto-ester (177) is also a preparatively useful method. 

Diacetoxy-1,1,3,3-tetrabutyldistannoxane, Sn-00360 Diazidodiphenylplumbane, Pb-00110 (l-Diazo-2-ethoxy-2-oxoethyl)trimethyllead, in Pb-00038 (l-Diazo-2-ethoxy-2-oxoethyl)trimethyltin, in Sn-00088 (Diazomethylene)bis[trimethylplumbane], see Pb-00065 (Diazomethyl)trimethylgermane, Ge-00043 (Diazophenylmethyl)trimethylgermane, see Ge-00126 Diazo(triethylgermyl)acetic acid, see Ge-00101 l-Diazo-l-(triethylgermyl)-2-propanone, Ge-00113 Diazo(trimethylplumbyl)acetic acid, Pb-00038 [Diazo(trimethylplumbyl)methyl]trimethylsilane, see Pb-00064 Diazo(trimethylstannyl)acetic acid, Sn-00088 Dibenzyldichlorostannane, Sn-00285... 

Preparation by demethylation of a-acetoxy-p-methoxyacetophenone (SM) with aluminium chloride in refluxing benzene for 3 h (80%). In the reaction, deacetylation takes place simultaneously. SM was obtained by treatment of a-chloro-p-methoxyacetophenone with potassium acetate in ethanol [5068]. Preparation by action of boron trifluoride etherate with p-hydroxyphenyl diazomethyl ketone (SMI) in nitromethane under nitrogen at 22° for 15 min (81%). SMI, preparation given, melted at 145-150° (d) [5069]. 

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