41653-95-6Relevant academic research and scientific papers
Transition Metal-Catalyzed Intramolecular Cyclization of 1,5- And 1,6-Dienes via Direct Cleavage and Addition of the Carbon-Hydrogen Bond
Fujii, Naoaki,Kakiuchi, Fumitoshi,Yamada, Airi,Chatani, Naoto,Murai, Shinji
, p. 285 - 298 (1998)
Ruthenium- and rhodium-catalyzed intramolecular C-H/olefin coupling reactions of 1-(2-pyridyl)-, 1-(2-imidazolyl-, and 1-(2-oxazolyl)-1,5-dienes proceeded in a regiospecific manner to give 5-membered ring products. Their 1,6-diene analogues are also applicable to the cyclization reaction to give the corresponding 5- and 6-membered carbocycles. For the cyclization of the pyridine derivatives, [RhCl(PPh3)3] showed the highest catalytic activity with respect to efficiency and selectivity. When the imidazole derivatives were employed to the cyclization reaction, the combination of the rhodium(I) complex and the relatively sterically bulky phosphine (e.g., PCy3 and PPFOMe) was a quite effective catalyst system. In the case of the oxazoles, the ruthenium complex, [Ru(H)2(CO)(PPh3)3], showed the highest activity among the catalysts examined. These catalytic reactions usually proceed at 120°C. The [RhCl(PPh3)3]-catalyzed cyclization reaction of 2-[(1E)-4,4-dimethyl-1,5-hexadienyl]pyridine smoothly proceeded even at room temperature to give the corresponding cyclized product in 93% yield after 24 h. A hybrid catalyst system containing the rhodium(I) and both PPh3 and P(o-tolyl)3 had a slightly better catalytic activity compared with that of [RhCl(PPh3)3]. The intramolecular cyclization can be also applied to the C-H/CO/olefin coupling reactions. These carbonylation reactions gave the 5-membered ring ketones exclusively. The intramolecular C-H/olefin coupling reactions provide a new entry for constructing carbocyclic compounds from 1,n-dienes.
Bidentate auxiliary-directed alkenyl C-H allylation: Via exo-palladacycles: Synthesis of branched 1,4-dienes
Shen, Cong,Lu, Xiunan,Zhang, Jian,Ding, Liyuan,Sun, Yaling,Zhong, Guofu
supporting information, p. 13582 - 13585 (2019/11/14)
An alkenyl C-H allylation by an exo-palladacycle intermediate is demonstrated, employing unactivated (Z)-Alkenes and allyl carbonates. With the use of an 8-Aminoquinoline (AQ) derived amide as the directing group, the N,N-bidentate-chelation-Assisted C-H activation protocol proceeded under mild and oxidant-free conditions with excellent selectivity. The utility of this approach is demonstrated by the preparative scale, selective conversion of inseparable Z/E alkenes and ready removal of the amide auxiliary to provide the corresponding ester.
Ti-direct, powerful, stereoselective aldol-type additions of esters and thioesters to carbonyl compounds: Application to the synthesis and evaluation of lactone analogs of jasmone perfumes
Nagase, Ryohei,Matsumoto, Noriaki,Hosomi, Kohei,Higashi, Takahiro,Funakoshi, Syunsuke,Misaki, Tomonori,Tanabe, Yoo
, p. 151 - 159 (2008/03/28)
An efficient TiCl4-Et3N or Bu3N-promoted aldol-type addition of phenyl and thiophenyl esters or thioaryl esters with aldehydes and ketones was performed (total 46 examples). The present method is advantageous from atom-economical and cost-effective viewpoints; good to excellent yields, moderate to good syn-selectivity, substrate variations, reagent availability, and simple procedures. Utilizing the present reaction as the key step, an efficient short synthesis of three lactone [2(5H)-furanone] analogs of jasmine perfumes was performed. Among them, the lactone analog of cis-jasmone had a unique perfume property (tabac). The Royal Society of Chemistry.
Penicillin acylase-mediated synthesis of 2-acetyl-1-pyrroline and of 2-propionyl-1-pyrroline, key roast-smelling odorants in food. Inclusion complexes with i-cyclodextrin and their NMR and MS characterization
Favino, Tito Fabrizio,Fronza, Giovanni,Fuganti, Claudio,Fuganti, Daniela,Grasselli, Piero,Mele, Andrea
, p. 8975 - 8979 (2007/10/03)
The synthesis of the strong natural roast odorants 1 and 2 is achieved from the C-6 isomeric alcohols 16 and 21 via the acetylenic C-6 and C-7 amines 8 and 9. Key step in the process is the hydrolysis of the W-phenylacetamides 12 and 13 by means of immobilized penicillin acylase, which affords the l-amino-4,5-diketones 14 and 15, spontaneously ring closing to 1 and 2. These latter compounds form inclusion complexes with/?-cyclodextrin, as demonstrated by NMR measurements in deuterated water and FAB-MS spectra.
Biosynthesis of tetronasin: Part 6. Preparation of structural analogues of the diketide and triketide biosynthetic precursors to tetronasin
Less, Simon L.,Handa, Sandeep,Millburn, Karen,Leadlay, Peter F.,Dutton, Christopher J.,Staunton, James
, p. 3515 - 3518 (2007/10/03)
The preparation of three analogues of the putative diketide biosynthetic precursor (2) and eight analogues of the putative triketide biosynthetic precursor (3) of the acyl tetronic acid ionophore tetronasin, as N-acetylcysteamine thioesters (4), (5), (6), (12), (13), (14), (15), (22), (23), (24) and (25) is described. Five examples are 19F-labelled; a new, enantiospecific method for the creation of a fluorinated quarternary α-centre is presented.
Xanthate Transfer Cyclization of Glycolic Acid-Derived Radicals. Synthesis of Five- to Eight-Membered Ring Ethers
Udding, Jan H.,Giesselink, J. P. M.,Hiemstra, Henk,Speckamp, W. Nico
, p. 6671 - 6682 (2007/10/02)
A novel method for the preparation of functionalized five- to eight-membered ring ethers is described.This method involves the xanthate transfer radical cyclization of 2-(alken-1-oxy)-2-acetic acid methyl esters 6 to give good yields of xanthate-substituted five- to eight-membered ethers 7 and/or 8, depending on the length of the carbon chain.These cyclic ethers are usually obtained as mixtures of diastereomers.The cyclizations are performed at 150-160 deg C in tert-butylbenzene with di-tert-butyl peroxide as the initiator.This group-transfer radical cyclization was successfully applied in a total synthesis of lauthisan (44).The use of benzoyl xanthate (56) as a catalyst allows a visible light-induced xanthate transfer cyclization to a tetrahydrofuran in high yield.
A facile synthesis of 1,4-diketones
Bergman,Nilsson,Wickberg
, p. 2783 - 2786 (2007/10/02)
1,4-Diketones may conveniently be synthesized by the addition of 2-methylcyclopropenyllithium to N-methoxy-N-methylcarboxamides followed by hydrolysis of intermediate cyclopropyl ketone adducts on silica gel. The new method has been applied to the synthesis of cis-jasmone.
Regio- and Stereoselective Ring Opening of ω-Alkenyllactones Using Organocopper Reagents
Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
, p. 3255 - 3264 (2007/10/02)
New synthetic methods are described for the preparation of (E)-3, (E)-4, and (E)-5-alkenoic acids by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopper reagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide.Both the organocopper reagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields.Alkadienoic acids were also obtained in good yields by the reactions of ω-alkenyllactones with divinyl- and diallylcuprates.Utilizing the ring opening of β-isopropenyl-β-propiolactone, homoterpenoid carboxylic acids were easly obtained in good yields.The ring opening of β-(1-chlorovinyl)-β-propiolactone afforded 4-chloro-3-alkenoic acids which were easly transformed to 4-oxoalkanoic acids and 4-oxo-2-alkenoic acids.
A REGIO DIASTEREOSELECTIVE BROMOLACTAMIZATION OF δ,γ-UNSATURATED THIOIMIDATES
Kano, Shinzo,Yokomatsu, Tsutomu,Iwasawa, Haruo,Shibuya, Shiroshi
, p. 359 - 362 (2007/10/02)
Cyclization of N-substituted E-δ,γ-unsaturated thioimidates (5a-f) with bis(collidine)bromonium perchlorate, followed by treatment with aqueous sodium carbonate affored the corresponding N-substituted threo-2-(2'-bromoalkyl)pyrrolidin-5-ones (10a-f), respectively, with high diastereoselectivity.Cyclization of Z-unsaturated thioimidate (9) gave the erythro-isomer (12).
NEW SYNTHETIC METHOD OF (Z)-4-ALKENOIC ACIDS USING RING-OPENING REACTION OF (Z)-4-HEXENOLIDE WITH ORGANOCOPPER REAGENT
Fujisawa, Tamotsu,Umezu, Kazuto,Kawashima, Masatoshi
, p. 1795 - 1798 (2007/10/02)
(Z)-4-Hexenolide reacted regioselectively with diorganocuprates to give (Z)-4-alkenoic acids in high yields.Synthetic utility was demonstrated by the convenient synthesis of cis-jasmone.
