3695-38-3Relevant academic research and scientific papers
Enantioselective synthesis of the apple aroma constituent 1,3,3-trimethyl-2,7-dioxabicyclo[2.2.1]heptane via asymmetric dihydroxylation
Brimble,Rowan,Spicer
, p. 1263 - 1266 (1995)
The enantiomers of 1,3,3-trimethyl-2,7-dioxabicyclo[2.2.1]heptane (1) were prepared in two steps from 6-methylhept-5-en-2-one using Sharpless asymmetric dihydroxylation.
Half-Sandwich Ruthenium Carbene Complexes Link trans-Hydrogenation and gem-Hydrogenation of Internal Alkynes
Guthertz, Alexandre,Leutzsch, Markus,Wolf, Lawrence M.,Gupta, Puneet,Rummelt, Stephan M.,Goddard, Richard,Farès, Christophe,Thiel, Walter,Fürstner, Alois
, p. 3156 - 3169 (2018/03/08)
The hydrogenation of internal alkynes with [Cp?Ru]-based catalysts is distinguished by an unorthodox stereochemical course in that E-alkenes are formed by trans-delivery of the two H atoms of H2. A combined experimental and computational study now provides a comprehensive mechanistic picture: a metallacyclopropene (??2-vinyl complex) is primarily formed, which either evolves into the E-alkene via a concerted process or reacts to give a half-sandwich ruthenium carbene; in this case, one of the C atoms of the starting alkyne is converted into a methylene group. This transformation represents a formal gem-hydrogenation of a ?€-bond, which has hardly any precedent. The barriers for trans-hydrogenation and gem-hydrogenation are similar: whereas DFT predicts a preference for trans-hydrogenation, CCSD(T) finds gem-hydrogenation slightly more facile. The carbene, once formed, will bind a second H2 molecule and evolve to the desired E-alkene, a positional alkene isomer or the corresponding alkane; this associative pathway explains why double bond isomerization and over-reduction compete with trans-hydrogenation. The computed scenario concurs with para-hydrogen-induced polarization transfer (PHIP) NMR data, which confirm direct trans-delivery of H2, the formation of carbene intermediates by gem-hydrogenation, and their evolution into product and side products alike. Propargylic aOR (R = H, Me) groups exert a strong directing and stabilizing effect, such that several carbene intermediates could be isolated and characterized by X-ray diffraction. The gathered information spurred significant preparative advances: specifically, highly selective trans-hydrogenations of propargylic alcohols are reported, which are compatible with many other reducible functional groups. Moreover, the ability to generate metal carbenes by gem-hydrogenation paved the way for noncanonical hydrogenative cyclopropanations, ring expansions, and cycloadditions.
Triquinanes from linear ketones via trimethylenemethane diyls
Lee, Hee-Yoon,Kim, Won-Yeob,Lee, Sejin
, p. 1407 - 1410 (2007/10/03)
Linear compounds containing a ketone and diene functional groups reacted with the anion of TMS-diazomethane to produce alkylidene carbenes that underwent intramolecular cyclopropanation followed by the formation of trimethylenemethane diyls which underwent [2+3] cycloaddition reaction to produce linearly fused triquinanes.
Facile entry to substituted decahydroquinoline alkaloids. Total synthesis of lepadins A-E and H
Pu, Xiaotao,Ma, Dawei
, p. 6562 - 6572 (2007/10/03)
Condensation of a L-alanine derived δ-bromo-β-silyloxy- propylamine with 1,3-cyclohexadione followed by alkylative cyclization produces a bicyclic enone. Diastereoselective Pt/C-catalyzed hydrogenation of this enone in HOAc provides a 5-oxo-cis-fused decahydroquinoline. Wittig olefination of this decahydroquinoline and subsequent epimerization of the resulting 5-formyl intermediate gives rise to a 5-β-formyl decahydroquinoline exclusively. In a parallel procedure, Peterson reaction of this decahydroquinoline and subsequent hydrogenation of the generated 5-exo-olefin provides a decahydroquinoline with a 5-α-substituent predominantly. For these two diastereoselective processes, using the intermediates without N-protection as the substrates is essential because the corresponding N-Boc intermediates give poor diastereoselectivity. The intermediate with β-form side chain is further converted into lepadins A-C via carbon chain elongation, while the intermediate with α-form side chain is transformed into lepadins D, E, and H and corresponding 5′-epimers via connection with two sulfones generated from two Sharpless epoxidation products. By comparison of the rotations and NMR data, the stereochemistry of lepadins D, E, and H is assigned as 2S,3R,4aS,5S,8aR,5′R.
Convenient synthesis of labdane and drimane analogues with o-quinol functionality
Meenakshi,Sivaramkrishnan,Padmakumar,Hadimani, Shreeshailkumar B.,Bhat, Sujata V.
, p. 4065 - 4076 (2007/10/03)
The Diels-Alder reactions of 4-carbomethoxy-o-benzoquinone with substituted-1,3-dienes give high yields of the drimane and labdane analogues containing an orthoquinol moiety.
Microwave assisted facile synthesis of Elvirol, Curcuphenol and Sesquichamaenol using Montmorillonite K-10 clay in dry media
Singh, Vasundhara,Khurana, Anupam,Kaur, Irvinder,Sapehiyia, Varinder,Kad, Goverdhan L.,Singh, Jasvinder
, p. 1766 - 1768 (2007/10/03)
Short, simple and convergent syntheses of the title compounds have been accomplished with good overall yields using a Montmorillonite K-10 clay catalyzed Friedel-Crafts alkylation reaction in 'dry media' as the key step.
First total synthesis of (±)-13-hydroxyneocembrene
Xing, Yacheng
, p. 595 - 600 (2007/10/03)
First total synthesis of (±)-13-hydroxyneocembrene (1), starting from 6-methyl-5-hepten-2-one (6) and geraniol (7), is described. The key steps are (i) the addition of sulfur-stabilized carbanion 12 to aldehyde 9, (ii) the synthesis of 18 by using phase-transfer catalyzed coupling reaction, and (iii) low-valent titanium-induced intramolecular coupling of oxo aldehyde 3 to afford the target molecule after the final deprotection.
STUDIES IN ACETALIZATION REACTIONS OF SOME TERPENES
Anac, Olcay,Talinli, Naciye
, p. 79 - 88 (2007/10/02)
The reactions of some terpenic ketones / aldehydes with alcohols were investigated in acidic medium.Some expected and unexpected products have been identified and possible mechanistic pathways leading to the products are discussed.
Carotenoids and Related Compounds. Part 43. Synthesis of Substituted α-Ionones, and of Diastereoisomers of Decaprenoxanthin.
Chopra, Akash K.,Khambay, Bhupinder P. S.,Madden, Hugo,Moss, Gerard P.,Weedon, Basil C. L.
, p. 1612 - 1631 (2007/10/02)
Various 1,2-cyclopropane analogues of ψ-ionone have been prepared.Acid catalysed cyclisation of the hydroxymethyl derivative (17) gave the vinyl-α-ionone (29).After appropriate modification of the vinyl side chain, this was converted into isomers of decaprenoxanthin in which the cyclic end groups had the 2,6-trans configuration.
SYNTHESIS OF SINGLE ISOMERS (E OR Z) OF PROTECTED γ,δ-UNSATURATED KETONES BY THE HORNER-WITTIG REACTION
Cornish Christopher A.,Warren, Stuart
, p. 2585 - 2598 (2007/10/02)
The lithium derivative of the γ-diphenylphosphinoyl ketal (10a) added to aldehydes and ketones to give stable Horner-Wittig intermediates (11) which were separated and converted into single isomers (E or Z) or γ,δ-unsaturated ketals (12). erythro-Adducts (11) and hence Z-(12), were selectively formed by addition of aldehydes and threo adducts (11), and hence E-(12), by reduction of the corresponding α-diphenylphosphinoyl ketones (13), prepared by acylation of the same γ-diphenylphosphinoyl ketal (10a).
