75993-79-2Relevant academic research and scientific papers
Masked ω-lithio ester enolates: Synthetic applications
Yus, Miguel,Torregrosa, Rosario,Pastor, Isidro M.
, p. 330 - 348 (2007/10/03)
The protocol of lithiation by means of lithium and a catalytic (5% molar) amount of DTBB (4,4'-di-tert-butylbiphenyl), applied to ω-chloro ortho ester 6 under Barbier-type conditions gives, after final acid-catalyzed methanolysis, the corresponding functionalized esters 8 or 9 (for chlorotrimethylsilane as electrophile) or, after ortho ester deprotection and acid catalyzed treatment, the δ-lactones 11. The procedure is also practical for bicyclic ortho esters 14: the β-chloro OBO ester derivate generates the γ-lactones 15 and the γ-chloro OBO ester gives corresponding esters 8.
A new synthesis of the 2,2,3,5,6,6-substituted tetrahydropyran aplysiapyranoid A and its 5-epimer
Hartung, Jens,Greb, Marco
, p. 6091 - 6093 (2007/10/03)
The vanadium(V)-catalyzed oxidation of bromide in the presence of methyl (E)-2-(1-hydroxy-1-methylethyl)-5-phenyl-4-hexenoate furnished 5,6-trans-5-bromo-6-phenyl-2,2,6-trimethyl-3- methyloxycarbonyltetrahydropyran, which was converted into the marine nat
Masked β-, γ- and δ-lithium ester enolates: Useful reagents in organic synthesis
Pastor, Isidro M.,Yus, Miguel
, p. 1029 - 1032 (2007/10/03)
The reaction of ω-chloro orthoesters 1 with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5% molar) in the presence of different electrophiles [ButCHO, PhCHO, (CH2)5CO, Et2CO, PhCOMe, PhCH=NPh, Me3SiCl] in THF at -78°C leads, after hydrolysis and acid-catalysed methanolysis, to functionalised methyl esters 2. In the case of chlorotrimethylsilane, hydroxyethyl esters 2′ are isolated. The reaction is also applied to bicyclic orthoesters 3: whereas β-chloro derivatives and carbonyl compounds gives directly γ-lactones 4 after hydrolysis, the corresponding γ-chloro derivative affords the expected methyl esters after methanolysis.
LIGHT-INDUCED FREE-RADICAL REACTIONS OF 2-METHOXY-6-METHYLTETRAHYDROPYRAN: IRREVERSIBLE RING OPENING AND MULTISITE HYDROGEN ABSTRACTION
Babcock, Bruce W.,Dimmel, Donald R.,Graves, David P.,McKelvey, Ronald D.
, p. 736 - 742 (2007/10/02)
Acetophenone-initiated photodegradation of cis-2-methoxy-4-methyltetrahydropyran (7) in benzene solvent produced six products.The structures of the products, and studies using optically active 7, showed that hydrogen abstraction occurs at both C-2 and C-6 of the tetrahydropyran ring.The products derived from the C-2 radical indicated two pathways for this radical: ring opening and loss of methyl, which is consistent with previous work on other similar systems.Results with optically active 7 showed that the ring-opening pathway is irreversible.Generation of an open-chain radical independently also showed that cyclization to a six membered ring does not occur.The products from the photodegradation were trans-2-methoxy-6-methyltetrahydropyran (8), methyl hexanoate (10), 6-methyltetrahydropyran-2-one (9), methyl 5-phenylhexanoate (11), 1,7-dimethyl-7-phenyl-6,8-dioxobicyclooctane (13), and 2-methoxy-2-(1-phenyl-1-hydroxyethyl)-6-methyltetrahydropyran (12).The yield of lactone 9 was found to be sensitive to the amount of residual oxygen present during the photolysis.
