Asymmetric alkoxycarbonylation catalysts

Palladium complexes bearing chiral monodentate phosphine ligands 592 (R = H, Ph) are effective catalysts for asymmetric alkoxycarbonylation of allyl phosphates <1997TL8227>. 

Asymmetric hydrogenation-based processes using a highly active and stereoselective catalyst generate relatively little waste. The asymmetric hydrogenation of readily preparable a-hydroxycarbonyl- or tz-alkoxycarbonyl-suInstituted enamrdes has frequently been applied to the preparation of unnatural a-amrno acids with a wide variety of side chains since the successful application of L-Dopa (Scheme 9.4) [13h]. 

Oxidative alkoxycarbonylation asymmetric carbonylation, 11, 467 catalyst development, 11, 467 mechanism, 11, 466 Oxidative amination, olefins, 10, 155 Oxidative cleavage, mechanisms, 1, 103 Oxidative promoters, in Pauson-Khand reaction with dicobalt octacarbonyl, 11, 337... 

Incidentally, cyclopropanation, one of the carbon-carbon bond formation reactions, is a useful reaction by using diazo compounds to give a variety of keto or alkoxycarbonyl cyclopropane derivatives, for example, crythantimates and their analogues as popular insectsides [2]. The cyclopropanation reactions have often been carried out with the use of copper or rhodium catalysts however, this results in stereochemical problems of trans-cis selectivity or asymmetric induction [3]. 

Alkylation of sodium 1-(alkoxycarbonyl)methyIphosphonates proceeds equally with acetates in THF from low to room temperature or in DME at reflux. The asymmetric allylic alkylation of the sodium diethyl l-(ethoxycarbonyl)methylphosphonate with 3-acetoxy-l,3-diphenyl-l-propene and cyclic allylic acetates in the presence of a chiral palladium catalyst, prepared from chiral phosphine and palladium acetate, in THF at room temperature proceeds in good yields (44-88%) and high ec s. ... 

Asymmetric hydrogenation of 1,2-diacyl- and 1,2-bis(alkoxycarbonyl)-2,3,4,5-tetrahydro-1 diazepine-7-carboxylic acids (80), using optically active ruthenium diphenylphosphine catalysts, for example (81), proceeds in high yields and optical purities (Equation (16)) in a process that has been applied to the synthesis of an intermediate to the antihypertensive drug, cilazapril <93EUP570764>. 

The development of the first highly enantioselective cyanocarbonation of prochiral ketones promoted by a chiral base catalyst, such as a cinchona alkaloid derivative, was reported by Tian and Deng in 2006. " Importantly, the reaction complemented known enzyme- and transition metal based methods in substrate scope via its unique ability to promote highly enantioselective cyanocarbonation of sterically hindered simple dialkyl ketones. Mechanistic studies provided experimental evidence to shed significant light on the asymmetric induction step in which the modified cinchona alkaloid acted as a chiral nucleophilic catalyst. Moreover, experimental evidence supported the mechanistic proposal that the enantioselectivity determination step in the cyanocarbonation was a DKR of the putative intermediates G and H via asymmetric transfer of the alkoxycarbonyl group (Scheme 2.105). 

Trost et al. reported the first asymmetric total synthesis of pseudolaric acid B by exploiting a rhodium-catalyzed intramolecular [5-1-2] cycloaddition reaction of a vinylcyclopropane with an alkyne (Scheme 8.2) [4]. The vinylcyclopropane having a tethered alkyne moiety 12 was synthesized from chiral precursors 9 and 11. Treatment of 12 with a cationic rhodium(1) catalyst promoted the [5-1-2] cycloaddition reaction to form a [5.3.0]bicyclic skeleton of 13 in a diastereoselective fashion. A few steps of functional group transformations provided the alkoxycarbonyl... 

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