Total Synthesis of (+)-Phomactin A Using a B-Alkyl Suzuki Macrocyclization
摘要:
A total synthesis of (+)-phomactin A is described using a B-alkyl Suzuki macrocyclization to incorporate the isolated trisubstituted olefin. This macrocyclization was accomplished with the sensitive hydrated furan ring in place. (R)-(+)-pulegone was used to establish the highly substituted cyclohexene core of the molecule.
Mimicking Polyolefin Carbocyclization Reactions: Gold-Catalyzed Intramolecular Phenoxycyclization of 1,5-Enynes
摘要:
PPh3AuNTf2 promotes highly efficient intramolecular phenoxycyclization reactions on 1,5-enynes under mild conditions. The original tricyclic and functionalized heterocycles were isolated in good to excellent yields. The 6-endo cyclization process is predominant and operates via a biomimetic cascade cation-olefin process. The efficiency of this system was further demonstrated in the cycloisomerization reaction of a 1,5,9-dienyne.
A Synthetic Approach toward Nitiol: Construction of Two 1,22-Dihydroxynitianes
作者:Michael S. Wilson、Jacqueline C. S. Woo、Gregory R. Dake
DOI:10.1021/jo0604585
日期:2006.5.1
nitiol has culminated in the construction of two epimeric hydroxylated derivatives, the 1,22-dihydroxynitianes. Key stereodefining steps in the construction of the A-ring fragment (13) were the use of a siloxy−epoxide rearrangement reaction, a Pauson−Khand reaction, a Norrish 1 photochemical cleavage reaction, and a highlyregio- and stereoselective hydrostannylation reaction of an ynoate. The stereochemistry
Cascade Cyclizations of Acyclic and Macrocyclic Alkynones: Studies toward the Synthesis of Phomactin A
作者:Jennifer Ciesielski、Vincent Gandon、Alison J. Frontier
DOI:10.1021/jo4007514
日期:2013.10.4
closure, while cyclizations using BF3·OEt2 as promoter occurred reversibly. For both acyclic and macrocyclic alkynones, high diastereoselectivity was observed in the intramolecular aldol reaction. The MgI2 protocol for cyclization was applied to the synthesis of advanced intermediates relevant to the synthesis of phomactin natural products, during which a novel transannular cation–olefin cyclization was
Efficient biomimetic tandem cyclization catalyzed by Hg(OTf)2 was achieved to give tricyclic 4 and tetractyclic 6 in high catalytic turnover. Structures of cyclization products were confirmed by X-ray diffraction study.
Mechanism of the nitrous acid-induced dealkylation of trisubstituted (terminal isopropylidene) olefins to form acetylenes
作者:E.J. Corey、William L. Seibel、John C. Kappos
DOI:10.1016/s0040-4039(00)96659-0
日期:1987.1
Evidence is presented that the conversion of olefins of the type RCHC(CH3)2 to acetylenes of structure RCCCH3 by the action of sodium nitrite in aqueous acetic acid proceeds by a sequence involving two nitrations, Nef conversion of one nitro group to carbonyl, ring closure to an isoxazolone N-oxide and fragmentation to carbondioxide, NO and the acetylene.