- Total Synthesis of (±)-Liphagal via Organic-Redox-Driven Palladium-Catalyzed Hydroxybenzofuran Formation
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A synthetic route to liphagal, a natural PI3Kα inhibitor isolated from Aka coralliphaga, was established. The present route features an organic redox process where an alkynylquinone undergoes reductive cyclization in the presence of a hydroquinone derivative such as hydroxyquinol (1,2,4-benzenetriol) and catalytic PdCl2 to provide a substituted benzofuran suitable for accessing the natural product. The benzofuran formation takes place via the redox transformation between the alkynylquinone and the electron-rich hydroquinones followed by the concomitant Pd(II)-catalyzed oxycyclization of the resultant alkynylhydroquinone.
- Tao, Eriko,Inoue, Masaki,Jeong, Taejoo,Kim, In Su,Yoshimitsu, Takehiko
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p. 9064 - 9070
(2020/07/14)
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- Enantioselective inhibition of squalene synthase by aziridine analogues of presqualene diphosphate
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(Figure Presented) Squalene synthase catalyzes the conversion of two molecules of (E,E)-farnesyl diphosphate to squalene via the cyclopropylcarbinyl intermediate, presqualene diphosphate (PSPP). Since this novel reaction constitutes the first committed step in sterol biosynthesis, there has been considerable interest and research on the stereochemistry and mechanism of the process and in the design of selective inhibitors of the enzyme. This paper reports the synthesis and characterization of five racemic and two enantiopure aziridine analogues of PSPP and the evaluation of their potencies as inhibitors of recombinant yeast squalene synthase. The key aziridine-2-methanol intermediates (6-OH, 7-OH, and 8-OH) were obtained by N-alkylations or by an N-acylation-reduction sequence of (±)-, (2R,3S)-, and (2S,3R)-2,3-aziridinofarnesol (9-OH) protected as tert-butyldimethylsilyl ethers. SN2 displacements of the corresponding methanesulfonates with pyrophosphate and methanediphosphonate anions afforded aziridine 2-methyl diphosphates and methanediphosphonates bearing N-undecyl, N-bishomogeranyl, and N-(α-methylene)bishomogeranyl substituents as mimics for the 2,6,10-trimethylundeca-2,5,9-trienyl side chain of PSPP. The 2R,3S diphosphate enantiomer bearing the N-bishomogeranyl substituent corresponding in absolute stereochemistry to PSPP proved to be the most potent inhibitor (IC50 1.17 ± 0.08 M in the presence of inorganic pyrophosphate), a value 4-fold less than that of its 2S,3R stereoisomer. The other aziridine analogues bearing the N-(α-methylene)bishomogeranyl and N-undecyl substituents, and the related methanediphosphonates, exhibited lower affinities for recombinant squalene synthase.
- Koohang, Ali,Bailey, Jessica L.,Coates, Robert M.,Erickson, Hans K.,Owen, David,Poulter, C. Dale
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supporting information; experimental part
p. 4769 - 4777
(2010/09/10)
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- Zirconium-catalyzed asymmetric carboalumination of alkenes: ZACA-lipase-catalyzed acetylation synergy
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ZACA-lipase-catalyzed acetylation tandem reactions provide highly efficient and selective routes to either (R)- or (S)-2-methyl-1-alkanols, making, for the first time, the ZACA-based asymmetric synthesis of 2-methyl-1-alkanols widely applicable and satisfactory.
- Huang, Zhihong,Tan, Ze,Novak, Tibor,Zhu, Gangguo,Negishi, Ei-Ichi
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p. 539 - 545
(2008/02/08)
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- Enantioselective synthesis of ent-stellettamide A: Asymmetric dipolar cycloadditions with Me3SiCHN2
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We report an enantioselective synthesis of ent-stellettamide A. Efficient entry into the indolizidine is possible through the application of a diastereoselective dipolar cycloaddition reaction of Me3SiCHN2.
- Whitlock, Gavin A.,Carreira, Erick M.
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p. 2007 - 2022
(2007/10/03)
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- THE TOTAL SYNTHESIS OF 10-(R,S)-C30 BOTRYOCOCCENE AND BOTRYOCOCCANE AND A NEW SYNTHESIS OF A GENERAL INTERMEDIATE TO THE BOTRYOCOCCENE FAMILY.
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The first synthesis of a C-30 botryococcene has been achieved by using a modified Julia reaction for the key coupling of fragments (2) and (3).The same strategy has been used in a new synthesis of a known synthetic precursor to the entire botryococcene family.
- Hird, Nicholas W.,Lee, Thomas V.,Leigh, Alistair J.,Maxwell, James R.,Peakman, Torren M.
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p. 4867 - 4870
(2007/10/02)
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