Enantiomerically pure γ-oxidofunctionalised organolithium compounds from chiral oxetanes

Four Unidentified Compounds Isolated from the Stem Barks of Aphanamixis polystachya and Their NO Production Inhibition in LPS Activated RAW 264.7 Cells

Phytochemical study on the methanol extract of the stem barks of Aphanamixis polystachya led to the isolation of four previously undescribed (1-4) and ten known compounds (5-14). Their chemical structures were elucidated to be 11-methoxysawaranospiroride C (1), 6α,9S,10,13-tetrahydroxymegastigmane-3-one (2), 11-hydroxyaphanamixin B (3), (2Z,6E,13E)-2,6,13-triene-11,15-dihydroxyphytanic acid (4), cinnacasside D (5), cinnacasside E (6), vilsonol F (7), (3S,5R,6S,7E,9R)-3,5,6,9-tetrahydroxy-7-en-megastigmane (8), (3S,5R,6R,7E,9R)-3,6,9,10-tetrahydroxy-7-en-megastigmane (9), citroside A (10), threo-1-(3,4,5-trimethoxyphenyl)-1,2,3-propanetriol (11), 3,4,5-trimethoxyphenyl-1-O-β-D-glucopyranoside (12), p-coumaric acid (13), ferulic acid (14) by HR-ESI-MS, ECD, 1D-, and 2D-NMR spectra. Compounds 1, 3, 4, and 9 showed NO production inhibitory activity in LPS activated RAW 264.7 cells with IC50 values of 42.0, 67.9, 20.5, and 78.6 μM, respectively, while the remaining compounds were inactive with IC50 values over 100 μM.

Straightforward Synthesis of Spirocyclic Tetrahydrofurans by a Reductive MCR/Iodoetherification Sequence

A straightforward and modular sequence for the synthesis of substituted spirocyclic tetrahydrofurans is described. The strategy relies on a reductive cobalt-catalyzed three-component reaction between a cyclic ketone, an acrylate, and a vinylic bromide followed by an intramolecular iodoetherification of the resulting γ-hydroxyalkene. Some functional group interconversions allowed the preparation of more varied spirocyclic compounds.

Synthesis of Three of the Four Diastereomers of 2-(1′,2′-Isopropylidenedioxyethyl)-3-Methyloxetane from D-Mannitol

The synthesis of three highly oxygenated, diastereomeric and optically active oxetanes from D-mannitol is described.

Synthesis of oxaspirannic building blocks by regioselective nitroso-Diels-Alder reactions

Spirocyclic structures: Nitroso-Diels-Alder reactions of 1,3-disubstituted cyclohexadienes were found to be regiodivergent, depending on the nitroso derivative used. Cycloaddition with Wightman's chloronitroso derivative was totally regio- and stereoselective. This methodology was applied to the synthesis of heterospiranic frameworks after N-O bond cleavage and cyclization (see scheme; Boc=tert-butoxycarbonyl, Tf=trifluoromethanesulfonyl).