T Butyl diazoacetate

Benzoylphenyidiazomethane 2 Butan-l-yl diazoacetate t-Butyl diazoacetate t-Butyl-2-diazoacetoacetate Diazoacetonitrile 2-Diazocyclohexanone Diazocyclopentadiene 1 -Diazoindine... 

C. t-Butyl diazoacetate. Into a 1-1. three-necked flask fitted with a stirrer, a dropping funnel, and a thermometer is placed a solution of 92.6 (0.50 mole) of /-butyl a-diazoacetoacetate in 150 ml. of methanol. After this solution has been cooled to 2-3° in an ice bath, a solution of sodium methoxide, prepared from 11.5 g. (0.50 g. atom) of sodium and 150 ml. of methanol, is added dropwise with stirring at such a rate that the reaction mixture remains within the temperature range 0-5° (about 30 minutes is required for the addition). After the addition is completed, the mixture is stirred in the ice bath for an additional 30 minutes. The red reaction solution is poured into 11. of ice water, and the resulting mixture is extracted with 500 ml. of ether. The aqueous phase is saturated with sodium chloride and extracted with two 500-ml. portions of ether (Note 8). The combined ethereal extracts are washed with 500 ml. of water and dried over anhydrous sodium sulfate. After the mixture has been filtered and the residue has been washed with ether, the bulk of the solvent... 

Diazomethane Di-t-butyl- Diazoacetic acid Diazomalonic Diphenyl-... 

The distillate is light yellow and contains some t-butyl diazoacetate,... 

Since then, a whole host of catalysts have been pubhshed, e.g. by Masamune, Kanemasa, Scott and Itagaki, for the enantioselective [2+l]-cycloadddition, but only a few give good yields for the reaction of 2,5-dimethylhexa-2,4-diene and the readily available t-butyl diazoacetate. [76] In the meantime, systematic optimisation work at Sumitomo has made highly active catalysts available, not only of the copper-salicylaldimine type, but also with bisoxazohne ligands, which enable excellent yields and selectivities. 

These positive results encouraged the authors to explore the activity of the chiral dicarhojg lic acids in reactions with different nucleophiles. Interesting results were obtained with dimethyl diazomethylphosphonate (up to 96% ee) and also in the trans-selective asymmetric aziridination with diazoacetamides 66. In the latter case, the traizs-selectivity was justified by an attack on the Re face of the imine differently from the attack on the Si face observed in the addition of t-butyl diazoacetate. This opposite facial enantioselectivily was due to the preference for the rotamer with the carboxamide group and aryl group of iV-Boc-imine in an antiperiplanar orientation and in this case a hydrogen bond between the amidic NH and Boc groups acted as a secondary factor. 

The same catalytic effect imparted by the empty capsule was observed changing the diazoacetate ester in the reaction with acrolein. In fact, with the t-butyl derivative the reaction with the capsule led to 97% yield, and with benzyl diazoacetate 54% yield of the corresponding cycloaddition product was observed. In both cases, the presence of the capsule occupied by the ammonium inhibitor led to a marked decrease of product formation. The higher conversions obtained in the presence of t-butyl diazoacetate as substrate were probably due to the good affinity with the cavity by means of CH-ji interactions. 

The catalytic effect of the capsule was extended also to the use of t-butyl diazoacetate, with other less reactive electron-poor alkenes following the reactions... 

A dry test tube containing catalyst (1.4 mg, 2 pmol, 2 mol%) and the imine (44.4 mg, 0.15 mmol, 1.5 equiv) was purged with nitrogen and then charged with toluene (1 mL). The resulting solution was treated with neat tert-butyl diazoacetate (14.2 mg, 0.1 mmol, 1 equiv) at r.t. After stirring for 24 h at ambient temperature, the mixture was subjected directly to FC on silica gel (hexanes ethyl acetate, 10 1 to 3 1) to give the product (32.9 mg, 75 pmol, 75% yield, 95% ee) as an oil. 

Diazoacetic acid silyl esters can be prepared by fra t-esterification of tert-butyl diazoacetate with trialkylsilyl triflate <1985JOM33>. Analogously prepared (alkenyloxy)silyl 203 and (alkynyloxy)silyl diazoacetates 206 underwent silicon-tethered 1,3-dipolar cycloaddition reactions as shown in Scheme 37 and Equation (38). Compound 205 resulted from a lateral criss-cross cycloaddition of the intermediate azine 204, which was formed from two molecules of 203 by diazo + diazo or diazo + carbene reaction <2000T4139>. On the other hand, when silyl diazoacetates 206 were kept in xylene at 142 °C for 1 h, bicyclic pyrazoles 207 were obtained (Equation 38). 

By modifying this process. Harper etal. (1951) obtained a mixture of the esters of the Z and E modifications, from which the active -isomer could be recovered by crystallisation. According to the findings of Matsumoto et al. (1963), using the t-butyl ester of diazoacetic acid in the presence of copper dust, ( )-chrysanthemic acid is formed stereoselectively. 

Thiopyrylium salts (62) are converted into diazo-esters (63) by the lithium salt of ethyl diazoacetate (see Scheme 4) further treatment with palladium(ii) complexes produces thiepins (64), the stability of which depends on R. Remarkably, the 2-propyl compound (64 R = CHMcj) extrudes sulphur at —70 °C, yet the t-butyl analogue (64 R = CMej) has a half-life of some 7 hours at 131... 

In additimi to EDA, a more bulky diazo reagent, tert-butyl diazoacetate (t-BDA), was found to be suitable for the catalytic system, generating the corresponding tert-butyl a, -unsaturated esters 21 with comparable yields (73-94%) and E-selectivity (E/Z 62/38-99/1) (1) ... 

The ruthenium(ll) complex 20175c,d and the cobalt complexes 21179a and 22197b are also able to produce remarkable enantioselectivities in intermolecular cyclopropanation reactions. For the cyclopropanation of styrene with alkyl diazoacetates, the following ee-values have been reported 20 /t/V-buty , 94% (trans), 85% (cis), /-menthyl, 95% (as), 76% (trans), /-menthyl, 86% (cis), 95% (trans) 21 ethyl, 75% (cis), 20% (trans) 22 tert-butyl, 73% (trans). It is interesting to note that a catalyst analogous to 20, but with copper(II) triflate instead of ruthenium, displayed only low enantiocontrol.220b... 

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