Alkoxy carbonyl

COOR esters alkoxy carbonyl alkyl -oate or carboxylate ... 

E)-alkene dipeptide isostere 48, 51, 63 alkenylepoxide 42 alkoxy carbonyl protecting group 32 P-alkoxy-a-amino esters... 

Addition to a-Hydroxy or a-Alkoxy Carbonyl Compounds Chelation-Controlled 1,2-Asymmetric Induction... 

I-Oialkoxy carbonyl compounds are a special class of chiral alkoxy carbonyl compounds because they combine the structural features, and, therefore, also the stereochemical behavior, of 7-alkoxy and /i-alkoxy carbonyl compounds. Prediction of the stereochemical outcome of nucleophilic additions to these substrates is very difficult and often impossible. As exemplified with isopropylidene glyceraldehyde (Table 15), one of the most widely investigated a,/J-di-alkoxy carbonyl compoundsI0S, the predominant formation of the syn-diastereomer 2 may be attributed to the formation of the a-chelate 1 A. The opposite stereochemistry can be rationalized by assuming the Felkin-Anh-type transition state IB. Formation of the /(-chelate 1C, which stabilizes the Felkin-Anh transition state, also leads to the predominant formation of the atm -diastereomeric reaction product. 

Thus chelation control " may lead to either product, depending on the relative stabilities of the respective ot- and /(-chelates. In cases with predominant formation of the anri-diastereomer, it is often difficult to establish whether the formation of a /(-chelate or an open-chain Felkin - Anh transition state is responsible for the observed stereochemistry the decision usually rests on plausibility considerations. Thus, with regard to the results obtained for a-alkoxy carbonyl... 

Molybdenum, tris(phenylenedithio)-structure, 1,63 Molybdenum alkoxides physical properties, 2,346 synthesis, 2,339 Molybdenum blue liquid-liquid extraction, 1,548 Molybdenum cofactor, 6,657 Molybdenum complexes acrylonitrile, 2,263 alkoxides, 3,1307 alkoxy carbonyl reactions, 2,355 alkyl, 3,1307 alkyl alkoxy reactions, 2,358 alkyl peroxides oxidation catalyses, 6,342 allyl, 3,1306... 

Tungsten complexes, 3, 973-1015 alkoxy carbonyl reactions, 2, 355 alkyl alkoxy reactions, 2, 358 amides... 

Finally the new ylides stabilized with sulfinyl but alkoxy carbonyl groups also behave in a more complex manner than for the simple sulfinyl ylide and the loss of both PhjPO and PhjP is observed [131]. Mixtures of products are obtained among which are alkenyl sulfides as major products but also sulfides and thioesters (Scheme 35). 

The heterocycles frequently carry substituents such as chloro, methylthio, or alkoxy-carbonyl. 

Some remarks concerning the scope of the cobalt chelate catalysts 207 seem appropriate. Terminal double bonds in conjugation with vinyl, aryl and alkoxy-carbonyl groups are cyclopropanated selectively. No such reaction occurs with alkyl-substituted and cyclic olefins, cyclic and sterically hindered acyclic 1,3-dienes, vinyl ethers, allenes and phenylacetylene95). The cyclopropanation of electron-poor alkenes such as acrylonitrile and ethyl acrylate (optical yield in the presence of 207a r 33%) with ethyl diazoacetate deserve notice, as these components usually... 

V-alkoxycarbonylamino add (Figure 1.10, path B) did not occur without immediate expulsion of the alkyl group, giving the amino-acid Af-carboxyanhydride (see Section 7.13). 2-Alkoxy-5(47/)-oxazolones are now recognized as intermediates in coupling reactions and are products that are generated by the action of tertiary amines on activated A-alkoxy carbonyl amino adds (see Section 4.16).20 22... 

All these reactions are examples of oxidative cyclocarbonylation-alkoxy-carbonylation. However, the Pdh/KI catalytic system turned out to be a very efficient catalyst also for promoting cyclization-alkoxycarbonylation processes. In fact, optimal conditions were found for selectively converting 4-yn-l-ols into tetrahydrofuran derivatives (Eq. 41) [107] through 5-exo-dig cyclization followed by alkoxycarbonylation (Scheme 19, path a). This kind of process was not possible for the propynyl, 3-yn-l-ol, and 2-ethynylaniline substrates, seen before, for stereoelectronic reasons [302], With the latter substrates, the endo cyclization mode (Scheme 19, path b), although in principle stereo electronically allowed, was not observed. 

Useful sources of these radicals were the hydrogen abstraction from alkyl formate and especially the decomposition by ferrous salts of mixtures of hydrogen peroxide and a-keto esters. The alkoxy-carbonyl radicals appear to be less nucleophilic than carbamoyl radicals. 

Rl is generally an alkyl group and R2 may be alkyl, alkoxy-carbonyl, aryloxycarbonyl, dlalkoxyphosphlnothloyl, alkyl-sulfonyl, arylsulfonyl, dlalkylamlnosulfonyl or (alkyl)(aryl)-amlnosulfonyl. 

Much less attention has been focused on carbonylation reactions in ionic liquids. The biphasic palladium-catalyzed alkoxy carbonylation of styrene. Scheme 2, in [bmim][BF4]—cyclohexane has been reported. ... 

Useful comparisons may be made here with the corresponding alkoxy-carbonyl radicals, C02Me and C02Et, for which values (6) for D4 of around —10 kcal. per mole have been advanced. These radicals C02R,... 

Fast alle N-Derivate der Kohlensaure lassen sich in irgendeiner Weise, z. B. durch Reduktion oder Hydrolyse, unter Bildung von Aminen spalten. Praktische Bedeutung besitzt unter anderem die reduktive Spaltung von N-substituierten Carbamidsaure-alkylestern (insbesondere von unsubstituierten oder substituierten Benzylestern), da diese N-Alkoxy-carbonyl-Derivate weite Anwendung als N-geschiitzte Amine, Aminosauren usw. finden... 

SCHEME 8. Schematic representation for the chelate-controlled addition of an organometaUic reagent (M—R) to the carbonyl group of a chiral a-alkoxy carbonyl compound (17). Two diastere-omers 18 with different orientation of R with respect to CH2R can be obtained. The syn diastereomer is obtained when the nucleophihc attack of R takes place on the same face of the plane, defined by the carbonyl group and the R-substituted carbon atom, where CH2R is located in the chelate complex... 

The addition paths of two separated MeMgCl molecules to the carbonyl group of chiral a-alkoxy carbonyl compounds, which are shown in Schemes 8 and 9 and in Figure 11 in Section IV, were traced. However, in these models, one MeMgCl molecule bridges two oxygen atoms and acts merely as a catalyst. Instead, the Schlenck dimer (MeMgCl)2 should be considered for the carbonyl reactant coordination. 

FIGURE 18a. Carbonyl addition process for the alkoxy carbonyl compound model corresponding to that of Scheme 17a-l... 

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