119905-76-9Relevant academic research and scientific papers
Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols
Ye, Ke-Yin,Mccallum, Terry,Lin, Song
supporting information, (2019/06/24)
Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely, bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton transfer/electron transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.
Formal total synthesis of (-)-dendrobine using zirconium-promoted reductive cyclization
Uesaka,Saitoh,Mori,Shibasaki,Okamura,Date
, p. 5633 - 5642 (2007/10/02)
The alkaloid (-)-dendrobine was synthesized from (+)-calvone by a short sequence using zirconium-promoted reductive cyclization. The absolute configuration of a synthetic intermediate was determined by an improved version of Mosher's method.
Formal Total Synthesis of (-)-Dendrobine Using Zirconium Promoted Cyclization. Determination of the Absolute Configuration of the Intermediary Tricyclic Ketone
Mori, Miwako,Saitoh, Fumihiko,Uesaka, Noriaki,Shibasaki, Masakatsu
, p. 213 - 216 (2007/10/02)
The optical purity of (-)-dendrobine synthesized using zirconium promoted cyclization was improved and the absolute configuration of the intermediary tricyclic ketone was determined using the improved Mosher's method developed by Kusumi.
Palladium-catalysed coupling of vinyl triflates with enynes and its application to the synthesis of 1α,25-dihydroxyvitamin D3
Mascarenas,Sarandeses,Castedo,Mourino
, p. 3485 - 3498 (2007/10/02)
We describe a general approach, based on the palladium-catalysed coupling of enynes with vinyl triflates, for the construction of dienynes related to vitamin D metabolites and analogues. As an application of this method, an efficient convergent synthesis of 1α,25-dihydroxyvitamin D3 starting from the Inhoffen-Lythgoe diol (6a) and natural carvones has been carried out (11 steps, 28% overall yield from 6a). This strategy allows labelling of the side chain in the final steps of the synthesis.
Palladium-catalyzed trimethylenemethane reaction to form methylenetetrahydrofurans. Reactions of substituted TMM precursors and mechanistic interpretation
Trost,King
, p. 408 - 422 (2007/10/02)
Alkyl-, phynyl-, vinyl-, and acetoxy-substituted palladium-trimethylenemethane (Pd-TMM) complexes react with aldehydes in the presence of organotin cocatalysts such as trimethylin acetate and trimethylin p-toluenesulfonate to give cycloadducts. The reactions of methyl-substituted TMM precursors 2a, 3, and 12 were studied most extensively. Two methylenetetrahydrofuran regioisomers, 10k and 10t, were produced in mixtures varying from 31:1 to 1:200 depending upon the TMM precursor, aldehyde, and cocatalyst. Conjugating substituents decrease the reactivity of the Pd-TMM complex, and only isomer 10t is available. The acetoxy substituent increases the reactivity of the organometallic and generated only 9k; however, the products cannot be isolated due to their lability. Electron-withdrawing substituents cause the complexes to be unreactive. Carveol-derived TMM precursors 23 and 2j give fused bicyclic products. Stereochemical analysis of these products showed that, contrary to olefin acceptors, aldehydes can, in some cases, attack the Pd complex on either face of the TMM moiety. These results indicate that trimethyltin chloride can be a very potent cocatalyst. The mechanism of the cycloaddition of aldehydes and, in particular, cocatalysis by organostannanes is discussed. The cocatalyst is believed to act by (1) aiding ring closure through the intermediacy of a stannyl ether and (2) acting as a Lewis acid to increase the rate of nucleophilic addition to the aldehyde.
SYNTHESIS OF α-AMINO ACIDS USING TRANSITION METAL CATALYSIS - ALKYLATION OF SCHIFF BASES DERIVED FROM α-AMINO ACID ESTERS (REGIO, STEREO-SELECTIVITY)
Genet, J.-P.,Juge, S.,Achi, S.,Mallart, S.,Montes, Ruiz J.,Levif, G.
, p. 5263 - 5276 (2007/10/02)
A general approach to the synthesis of γ,δ-unsaturated α-amino acid esters is described.Schiff bases derived from glycine and alanine esters were alkylated in the presence of palladium or molybdenium catalysts under neutral or basic conditions using allylic carbonates, esters or halides, (20-95 percent yield).These less stabilized nucleophiles reacted with the η3 allyl species on the side opposite to the palladium and they can be classified as soft nucleophiles.The regioselectivity was studied with various unsymmetrical electrophiles.After hydrolysis, several functionalized α-amino acids of biological interest (enzymes inhibitors) were obtained.Asymmetric palladium allylic alkylation of the benzophenone imine glycine methyl ester using Pd(OAc)2 + (+)DIOP was achieved with up to 68 percent ee; the enantioselective Pd-promoted alkylation of this new and useful prochiral nucleophile for the synthesis of α-amino acids is one of the highest ee known.
Some Novel Esters of Carveol
Ravindranath, B.,Srinivas, P.
, p. 666 - 667 (2007/10/02)
Reaction of limonene (1) with t-butyl hypochlorite yields carvyl chloride as the major product, which is readily converted into carvyl acetate, carveol and carvone.Several novel esters of carveol, namely cis and trans carvyl benzoate, cinnamate, phenoxyacetate and phenylacetate have also been prepared for the first time in a one-pot reaction of carvyl chloride with the corresponding zinc carboxylate.
