Enantioselective Syntheses of Pachastrissamine and Jaspine A via Hydroxylactonization of a Chiral Epoxy Ester

Synthetic Studies on a Pachastrissamine Sulfur Analogue: Synthesis of a 4-epi-Sulfur Analogue

A versatile synthetic procedure for a sulfur analogue of pachastrissamine (jaspine B), which involves the tandem thiolation-cyclization of a 1,4-ditosylate to construct a tetrahydrothiophene ring, was developed. Nucleophilic amino substitution of a tetrahydrothiophene-4-sulfonate with unexpected retention of the configuration afforded the sulfur analogue of 4-epi-pachastrissamine.

Practical Synthesis of Pachastrissamine (Jaspine B), 2-epi-Pachastrissamine, and the 2-epi-Pyrrolidine Analogue

The practical syntheses of pachastrissamine (jaspine B), 2-epi-pachastrissamine, and the 2-epimer of the pyrrolidine analogue were accomplished via the stereoselective reduction of an allylketone derived from commercially available diethyl D-tartrate and the cross-metathesis of an allyltetrahydrofuran or allypyrrolidine with 1-tridecene as key steps.

Formation of tetrahydrofurans via a 5-endo-tet cyclization of aziridines--synthesis of (-)-pachastrissamine

The formation of tetrahydrofurans from 2-hydroxyalkyl-oxirane or aziridine is reported. The 5-endo-tet cyclization/ring opening of aziridine proceeded smoothly to give tetrahydrofurans (THFs) under mild conditions. In contrast, the corresponding process of oxirane was unsuccessful and a sequence of SN2 substitution/cyclization was required to form THFs. The application of the process to prepare ent-(-)-pachastrissamine is described.

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C3-building block

Herein we present the synthesis of the anhydrophytosphingosine jaspine B and three of its stereoisomers using a carbohydrate-derived alkoxyallene in order to obtain the products in enantiopure form. Key step of the reaction sequence is the addition of the lithiated alkoxyallene to pentadecanal, setting the configuration at the later C-2 of the ring system. This reaction step proceeds with moderate selectivity and therefore leads to a stereodivergent approach to the natural product and its enantiomer. The gold-catalyzed 5-endo-cyclization affords the corresponding dihydrofurans, which after separation, azidation of the enol ether moiety and two subsequent reduction steps give the natural product and its stereoisomers.

Marine natural products

Covering: 2010. Previous review: Nat. Prod. Rep., 2011, 28, 196. This review covers the literature published in 2010 for marine natural products, with 895 citations (590 for the period January to December 2010) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1003 for 2010), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Asymmetric synthesis of Pachastrissamine (Jaspine B) and its diastereomers via η3-allylpalladium intermediates

A short route for the synthesis of Pachastrissamine (Jaspine B), an anhydrosphingosine derivative, and all three of its diastereomers is presented. The route consists of only 9 steps from the commercially available Garner's aldehyde. The furan framework is formed via an η(3)-allylpalladium intermediate.