Exiguolide synthesis

Karl Scheidt and co-workers at Northwestern have reported in ACIEE on their synthesis of exiguolide and you guessed it:  Prins cyclization was used to form the tetrahydropyran rings.

ACIEE paper

Candidaspongiolides

Tawnya McKee and co-workers from NCI have reported in Organic Letters on the isolation of candidaspongiolides that had selective biological activity against melanoma cell lines (LD50 of 19-174 nM).

OL paper

Aspergillide synthesis

Kozo Shishido and co-workers from the University of Tokushima have reported in Chem Comm on a transannular oxy-Michael reaction to access aspergillide.

Chem Comm paper

Orthodiffenes A-D

Biswanath Das and co-workers at IICT have published in Tetrahedron Letters on the isolation of orthodiffenes A-D. Orthodiffene A had an IC50 value of 3.66 micrograms/mL against HL-60 cell lines.

 

TL paper

Karlotoxin

Karlotoxin 2 was isolated and characterized by Mark Hamann and co-workers at the University of Mississippi.  This molecule possesses two tetrahydropyrans and some long chains and numerous stereocenters; moreover it has cytotoxic properties that wiped out fish populations in Maryland.  The compound was isolated from a dinoflagellate, Karlodinium veneficum.

JACS paper

Aspergillide A Progress

I always had the impression that DDQ only removes PMB groups but I guess I was wrong since this article shows that you can remove benzyl groups as well…I think this just means I need to think about that mechanism about reactions more carefully and also use that Greene book of Protective Groups in Organic Chemistry.  2,3-Dichloro-5,6-dicyanobenzoquinone (aka DDQ) is a very useful reagent that is deprotecting through a radical mechanism.   Alberto Marco and co-workers at Universitat de Valencia in Spain have recently published in JOC on their progress towards aspergillide A, which has a macrolide and a THP ring embedded in it – a characteristic similar to neopeltolide.

JOC paper

(5S)-5-Acetoxycaespitol

Halogenated metabolites from the Brazilian red alga Laurencia catarinensis were reported in the Journal of Natural Products by Vassilios Roussis and co-workers from the University of Athens.  (5S)-5-Acetoxycaespitol had IC50 values of 12.4, 11.7, and 13.1 micromolar against HT29, MCF17, A431 tumor cell lines respectively.

JNP paper

Rhoiptelol B

Chada Raji Reddy and co-workers at the Indian Institute of Chemical Technology have recently published in the European Journal of Organic Chemistry on the synthesis of rhoiptelol B, a tetrahydropyranyl compound.  They simply made the tetrahydropyran ring by intramolecular attack of a hydroxyl onto a ketone followed by reduction.

European Journal of Organic Chemistry paper

Cyclic Enol Ethers as Nucleophiles

Nancy Totah and co-workers at Syracuse University have recently published in Chemical Communications on the stoichiometric Lewis acid activation of carbonyl compounds to react with cyclic enol ethers to form substituted tetrahydropyranyl ketides.

Chemical Communications paper

Neopeltolide

Karl Scheidt and co-workers have recently published a full paper in JACS on their account of the synthesis of neopeltolide, a compound isolated from a sponge and also has nanomolar to subnanomolar IC50 values towards cancer cell lines.  The macrocyclic structure that contains a tetrahydropyran ring was formed via a Prins cyclization in one step using scandium triflate.

JACS paper