T-Butyl acetoacetate

The Ramberg-Backlund reaction has been utilized for the preparation of polyenes. 1,3-Butadienyl allyl sulfones 398 and 399 were transformed into the tri- and tetra-enes 400 and 401 by alkylcuprate addition and the Ramberg-Backlund-type S02 extrusion449. Julia and coworkers450 carried out the Michael addition of various nucleophiles such as ethanol, t-butyl acetoacetate and phenyl thioacetone to allyl dienyl sulfones 402 and then converted them to diallyl sulfones 403. The sulfones were transformed into isoprenoid, 404 by the Ramberg-Backlund reaction. 

Asymmetric [2 + 2] photocycloadditions. Acid-catalyzed condensation of t-butyl acetoacetate with (— )-menthone (1) results in two dioxacyclohexenones, 2 and 3, which are easily separable. Photocycloaddition of ( — )-2 with methylcyclo-butene gives mainly the adduct (4) which has the cis, anti, cis-configuration at the... 

Additional compounds suitable for studies of steric effects on keto-enol equilibria include a-methylacetylacetone (CH3COCHCH3COCH3), diethyhnalonate (CH3CH2OCO-CH2COOCH2CH3), ethyl benzoylacetate (C6H5COCH2COOCH2CH3), and t-butyl acetoacetate (CH3COCH2COOFBU). Some other possible compounds are hsted in Refs. 4 and 5. 

An improvement in this synthesis results from the use of the thallium salt of t-butyl acetoacetate in place of ethyl acetoacetate, and ethyl methylmalonyl chloride may replace the diacyl dihalide (75S259). 

Acyloin synthesis. In a novel synthesis by Lawesson and Gronwall t-butyl acetoacetate is prepared from diketene and t-butanol and alkylated, and the benzoyl oxy group is introduced in the a-position by reaction of the sodio derivative with dibenzoyl peroxide. Elimination of the /-butyl group and decarboxylation is accomplished by heating the ester at 160° with a catalytic amount of p-toluenesulfonic... 

Reaction with active-H compounds. The reagent is hydrolyzed by water to aceto-acetic acid and it reacts with alcohols to form the corresponding esters, as illustrated by a procedure for the preparation of t-butyl acetoacetate. The analogous reaction... 

In the early amidation approach, 2 may be assembled by condensation of aldehyde-amide 4 with 5-fluorooxindole 3. The aldehyde-amide would arise from a Knorr pyrrole reaction involving oxime 5 (derived from t-butyl acetoacetate) and (3-ketoamide 6, which can, in turn, be synthesized from diketene 7 and A,iV-diethylethylenediamine 8. 

Oxime 5 was synthesized by treatment of t-butyl acetoacetate with sodium nitrite in acetic acid. Reaction of 5 wim p-ketoamide 6 in me presence of zinc and acetic acid according to the classic Knorr pyrrole formation conditions led to pyrrole 12. Aimough mis reaction worked fairly well (60 to 70% yield), workup and product isolation proved problematic as the reaction scale was increased (>10 g). Typically, the products of Knorr reactions (when p-ketoesters are used instead of p-ketoamides) are isolated by a water knock-out at me end of me reaction. However, in the case of 12, me presence of me pendant amine functionality rendered precipitation of the product from an acidic reaction mixture impossible. Precipitation of me product required basic conditions unfortunately, at pH 9, gelatinous zinc salts crashed out of solution, making an extraction or isolation... 

A -ButenoUdes, 53, 339, 411 / Butoxybi (dimetliylainino)methane, 41 t-Butyl acetoacetate, 50, 51 1-r-ButylalIene oxide, 279 r-Butyl azidoformate, 41-42 r-Butylbenzene, 362... 

Inspired by their previous work dealing with enantioselective conjugate addition of t-butyl acetoacetate to crotonoylthiazolidinethione catalysed by a preformed nickel catalyst from/>-To 1-BINAP ligand 30, and by those of Kane-masa on enantioselective nickel-catalysed additions of thiols and 1,3-dike-tones to unsaturated acylpyrazoles and oxazolidinones with a chiral amine ligand, Evans et al. investigated the scope of enantioselective Michael... 

Synthesis of cyclopentenones utilizing allylphosphonates has been examined by Spilling and Yan. In the first step, the Pd-catalyzed, nueleophilic substitution reaction of (179) with t-butyl acetoacetate,... 

Cyanidiutn caldarlum) reduced aromatic ketones. Plant cell cultures (Nicotiana tabacum var. Samsun NN cells) reduced t-butyl acetoacetate to the corresponding (S)-alcohol with high optical yield. Radish (Raphanus sativus L.) sprout reduced a, a, a-trifluoro-acetophenone and Arabidopsis seedlings sprout reduced f-butyl acetoacetate to the corresponding chiral alcohol in eantiomeric excess. 

Nicotiana tabacum var. Samsun NN cells as a photosynthetic biocatalyst reduced t-butyl acetoacetate to tiie corresponding (S)-alcohol with a low chemical yield (46%) and optical )deld (13% ee) in e dark (Figure 11.7c). However, the reaction under illumination gave the corresponding (S)-alcohol with high chemical yield (83%) and optical 5deld (75% ee) in the natural atmospheric COj concentrations (0.04%). Furthermore, tire high atmospheric CO concentration (1.5%) improved both the chemical yield (up to 98%) and the optical yield (up to 98%) in the reaction. 

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