1471-03-0Relevant articles and documents
Understanding the competitive dehydroalkoxylation and dehydrogenation of ethers with Ti-C multiple bonds
Crestani, Marco G.,Olasz, Andras,Pinter, Balazs,Bailey, Brad C.,Fortier, Skye,Gao, Xinfeng,Chen, Chun-Hsing,Baik, Mu-Hyun,Mindiola, Daniel J.
, p. 2543 - 2550 (2013)
The divergent reactivity of a transient titanium neopentylidyne, (PNP)TiCtBu (A) (PNP = N[2-PiPr2-4- methylphenyl]2-), that exhibits competing dehydrogenation and dehydroalkoxylation reaction pathways in the presence of acyclic ethers (Et2O, nPr2O, nBu2O, tBuOMe, tBuOEt, iPr2O) is presented. Although dehydrogenation takes place also in long-chain linear ethers, dehydroalkoxylation is disfavoured and takes place preferentially or even exclusively in the case of branched ethers. In all cases, dehydrogenation occurs at the terminal position of the aliphatic chain. Kinetics analyses performed using the alkylidene-alkyl precursor, (PNP)TiCHtBu(CH 2tBu), show pseudo first-order decay rates on titanium (kavg = 6.2 ± 0.3 × 10-5 s-1, at 29.5 ± 0.1°C, overall), regardless of the substrate or reaction pathway that ensues. Also, no significant kinetic isotope effect (k H/kD ～ 1.1) was found between the activations of Et2O and Et2O-d10, in accord with dehydrogenation (C-H activation and abstraction) not being the slowest steps, but also consistent with formation of the transient alkylidyne A being rate-determining. An overall decay rate of (PNP)TiCHtBu(CH 2tBu) with a t1/2 = 3.2 ± 0.4 h, across all ethers, confirms formation of A being a common intermediate. Isolated alkylidene-alkoxides, (PNP)TiCHtBu(OR) (R = Me, Et, nPr, nBu, iPr, tBu) formed from dehydroalkoxylation reactions were also independently prepared by salt metatheses, and extensive NMR characterization of these products is provided. Finally, combining theory and experiment we discuss how each reaction pathway can be altered and how the binding event of ethers plays a critical role in the outcome of the reaction.
Efficient Stereoselective Synthesis of a Key Chiral Aldehyde Intermediate in the Synthesis of Picolinamide Fungicides
Li, Fangzheng,Good, Steffen,Tulchinsky, Michael L.,Whiteker, Gregory T.
, p. 2253 - 2260 (2019/10/16)
A highly stereoselective and efficient synthesis of (4S,5S,6S)-6-(benzyloxy)-5-phenoxy-4-propoxyheptanal, a key intermediate for syntheses of picolinamide fungicides, is described in this report. The synthesis features a scalable allylpropyl ether preparation, an efficient synthesis of the C1-C3 anti,syn-(S,S,S) stereotriad via a highly diastereoselective allylboration, and Cu-catalyzed phenylation of a sterically hindered secondary alcohol with BiPh3(OAc)2 followed by highly regioselective hydroformylation with the formation of a linear aldehyde. Excellent overall route efficiency was achieved (six steps and 39% yield) starting from readily available and inexpensive (S)-ethyl lactate.
Technological method for preparation of allyl ether compounds
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Paragraph 0059-0061, (2017/02/17)
The invention discloses a technological method for preparation of allyl ether compounds; the technological method can obtain the high-purity allyl ether compounds in low cost and high yield, has the advantages of high selectivity of the allyl ether compounds, less side reaction, easy separation and purification of the products, friendly technological process environment and the like, and is suitable for large-scale industrialized production.
Hydrogen-bond-activated palladium-catalyzed allylic alkylation via allylic alkyl ethers: Challenging leaving groups
Huo, Xiaohong,Quan, Mao,Yang, Guoqiang,Zhao, Xiaohu,Liu, Delong,Liu, Yangang,Zhang, Wanbin
supporting information, p. 1570 - 1573 (2014/04/17)
C-O bond cleavage of allylic alkyl ether was realized in a Pd-catalyzed hydrogen-bond-activated allylic alkylation using only alcohol solvents. This procedure does not require any additives and proceeds with high regioselectivity. The applicability of this transformation to a variety of functionalized allylic ether substrates was also investigated. Furthermore, this methodology can be easily extended to the asymmetric synthesis of enantiopure products (99% ee).
PROCESS FOR PRODUCING ETHER COMPOUNDS IN PRESENCE OF A COPPER (II) SALT
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Page 46-47, (2008/06/13)
A process for producing allylic ether compounds in presence of a catalyst comprising at least one Cu(II) salt by reaction of an allylic alcohol with either itself or another alcohol.
Hydrolysis and Alcoholysis of Esters of o-Nitrobenzenesulfonic Acid
Sendega,Makitra,Pirig
, p. 1438 - 1446 (2007/10/03)
The rate of solvolysis of esters of o-nitrobenzenesulfonic acid with water and C1-C4 alcohols is satisfactorily described by two-parametric Hammett-Taft equation with predominating effect of the electronic factor σ*. The effect of the structure of the hydrocarbon rest in the sulfonic ester group does not fit to this relationship.
Synthesis of benzyl/allyl alkyl ethers from corresponding magnesium alkoxides
Lin, Ji-Mao,Li, Hui-Hui,Zhou, Ai-Min
, p. 5159 - 5160 (2007/10/03)
In the presence of iodine, alcohols react with magnesium to produce magnesium alkoxides which are then treated with benzyl chloride or allyl bromide to produce benzyl alkyl ethers or allyl alkyl ethers.
Unimolecular Reactions of Isolated Organic Ions: Loss of Carbon Monoxide from the Oxonium Ion CH2=CHCH2+O=CH2 via Double Hydrogen Transfer
Bowen, Richard D.,Wright, Andrew D.,Derrick, Peter J.
, p. 501 - 507 (2007/10/02)
The reactions of the metastable oxonium ion CH2=CHCH2+O=CH2 have been investigated.This C4H7O+ species was generated by ionisation and alkyl radical loss from allyl ethyl or allyl propyl ether.CH2=CHCH2+O=CH2 is apparently ideally suited to fragmentation via simple cleavage to form the favourable products CH2=CHCH2+ and CH2O.However, at low internal energies, expulsion of a neutral species having a mass of 28 amu takes place essentially to the exclusion of CH2O loss. 2H- and 13C-labelling experiments reveal that it is carbon monoxide which is eliminated, via double hydrogen transfer between the developing products accessible to C-O bond fission.The role of ion-neutral complexes in these hydrogen transfer steps is discussed.
CHEMISTRY OF SYSTEMS OF THE ALLYL TYPE I. SYNTHESIS OF ALLYL AND 2-PROPYNYL ETHERS UNDER PHASE-TRANSFER CATALYSIS CONDITIONS
Ibragimov, I. I.,Tarasov, V. A.,Aliev, A. G.,Belyaeva, V. I.
, p. 1398 - 1402 (2007/10/02)
A convenient method was developed for the synthesis of allyl and 2-propynyl ethers under phase-transfer catalysis conditions, which make it possible to dispense with the use of an inert organic solvent and to ensure the practically complete conversion of the alkylating agent.
