Novel “Protecting Group-Dependent” Alkylation−RCM Strategy to Medium-Sized Oxacycles:  First Total Synthesis of (−)-Isoprelaurefucin

Abstract

[reaction: see text] A novel "protecting group-dependent" alkylation strategy was developed for complementary diastereoselective syntheses of alpha,alpha'-syn- and alpha,alpha'-anti-bis-alkenes 2 and 3, which represent ring-closing metathesis (RCM) substrates for medium-sized oxacycles. This principle has been applied to a stereoselective and concise total synthesis of (-)-isoprelaurefucin (4) in 14 steps in 12% overall yield from known epoxide 8.

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

“…In contrast, recent studies of enzyme-catalyzed halogenation reactions provided some useful insight into the biogenesis of Rhodomelaceae-derived metabolites. 429 Among these, vanadium bromoperoxidase (V-BrPO) is an abundant enzyme that was isolated from many algal species, including members of the genus Laurencia, and plays a key role in the biosynthesis of brominated molecules. 404 In 2004, the Butler group reported the first V-BrPO-catalyzed asymmetric bromination and cyclization of the sesquiterpene (E)-(+)-nerolidol (698) to produce α-, β-, and γ-snyderol (172, 173, and 699), as well as the (+)-3β-bromo-8-epicaparrapi oxide (194) and its stereoisomer 700 (Scheme 20).…”

Transition metals in organic synthesis: Highlights for the year 2005

“…Examples of synthetic targets include, 10-hydroxyasimicin [322], cylindramine [323], murisolins [324], norzoanthamine [325], salicylihalamide core [326], (+)-laudanosine and (−)-xylopine [327], 5,5-difluoroleukotrienes B 3 [328], dehydrocoelenterazine analogs [204], (−)-epiindolizidine 167B and 5E,9Z-indolizidine 223AB [329], (+)-allocyathine B 2 [128], amphidinolides T1 and T4 [330], (4E,6Z,10Z)-4,6,10-hexadecatrien-1-ol [331], diacetylenic spiroacetal enol ethers [332], epoxyquinoid compounds [53], heliophenanthrone [333], bulgaramine [334], (−)-siphonodiol [335], the ergoline skeleton [336], (−)-isoprelaurefucin [337], elipticine [338], pyranicin [339], peroxyacarnoates A and D [66], allocolchicinoid [340], (−)-217 A [341], DE ring system of upenamide [342], A2E [73], ␣-glycosylindole [343], mycolactones A and B [296], (+)-obtusenyne [344], tetradec-6-en-1,3-diyne-13-one [345], virol C and 1-dehydroxyvirol A [346], terreinol [347], (+)-trifluoromethyl monomorine [348], 2E,4E,6E,11Z-octadecatetraenoic acid [239], 7(S),17(S)-resolvin D5 [349], erogorgiaene [350], solamine analogs [351], longimicin C [352], furanopyrimidine nucleoside analogs [353] and polyacetylenic acids …”

“…The palladium-catalyzed alkoxy-carbonylation of organic halides and triflates was used in synthetic applications toward fumagalone analogs [503], Uhle's ketone and the ergoline skeleton [337], pyrrolizidines [504], pilcadin (Eq. (57)) [505], 1,2-anhydro methyl rocaglate [506], (+)-8-epi-xanthin [507], carbasugars [508] and 261C [509].…”

A Unifying Stereochemical Analysis for the Formation of Halogenated C15-Acetogenin Medium-Ring Ethers From Laurencia Species via Intramolecular Bromonium Ion Assisted Epoxide Ring-Opening and Experimental Corroboration with a Model Epoxide

“…[3][4][5] The synthetic challenges of medium-ring ether formation, control of the cis-or trans-α,α' ether stereochemistry, stereoselective halide incorporation and selective enyne or bromoallene formation has resulted in much synthetic interest, and state-of-the-art total syntheses over the last five decades have been continually reported. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The generally accepted biogenesis of this class of metabolites finds its origins in the isolation of C 15 -(3E,6R,7R)-laurediol 18 and its oppositely configured diol (3Z,6S,7S)-18 by Irie in 1972. 21 Later studies by Murai and co-workers 22 showed that the constitutional isomeric eight-membered medium-ring ethers deacetyllaurencin (1b) and prelaureatin (3) (with molecular formulae of C 15 H 21 BrO 2 ) were formed -albeit in very low yields -from the two diols respectively via lactoperoxidase (LPO) and (partially purified) bromoperoxidase (BPO)-catalyzed bromoetherifications with no apparent crossover between the two series (Scheme 1).…”