Tandem Ring‐Closing/Cross‐Metathesis Approach for the Synthesis of Synargentolide B and Its Stereoisomers

Abstract

The stereoselective syntheses of synargentolide B and its three stereoisomers have been accomplished from L‐(+)‐ and D‐(–)‐diethyl tartrates, D‐ribose, and D‐mannitol as chiral pool starting materials. The key step was a tandem ring‐closing/cross‐metathesis reaction in which lactone formation and fragment coupling were accomplished in one pot. The spectroscopic data of synthetic product 2c were in agreement with those reported for the natural product. Synargentolide B isolated by Rivett et al. and the compound isolated by Pereda‐Miranda et al. are not diastereomers, but rather they are identical.

A Divergent Synthesis of l‐arabino‐ and d‐xylo‐Configured Cyclophellitol Epoxides and Aziridines

“…For this, we turned our attention to the literature on nucleophilic allylation of aldehydes D. Madsen and co-workers thoroughly studied domino elimination-alkylation reactions of methyl iodofuranoside E affording products C directly. The isopropylidene-protected aldehyde D has been allylated using catalytic asymmetric Keck conditions [22] or by using allyl-zinc reagents, [23] but the isopropylidene protective group would implicate acidic deprotection in the final stages of the synthesis, conditions that may be incompatible with the targeted epoxides and aziridines. Apart from zinc-or indium-mediated Barbier additions to aldehyde D, [20,21] examples of Grignard-like allylations on the carbonyl group are scarce.…”

“…Apart from zinc-or indium-mediated Barbier additions to aldehyde D, [20,21] examples of Grignard-like allylations on the carbonyl group are scarce. The isopropylidene-protected aldehyde D has been allylated using catalytic asymmetric Keck conditions [22] or by using allyl-zinc reagents, [23] but the isopropylidene protective group would implicate acidic deprotection in the final stages of the synthesis, conditions that may be incompatible with the targeted epoxides and aziridines. We therefore decided to investigate the efficacy of 2,3-di-O-benzyl-2,3-dihydroxy-pent-4-enal (1), readily available according to the literature procedure, [16] as the starting material in our allylation studies.…”

Total synthesis of synargentolide B

“…In 1990, Pereda-Miranda et al reported (6R)-[(5R,6S)-diacetyloxy-(1S,2R)-dihydroxy-3E-heptenyl]-5,6-dihydro-2H-pyran-2-one 1 from the leaves of Mexican plant Hyptis oblongifolia. 8 Recently, Prasad et al 9 and Sabitha et al 10 established the structure of 1 by the total synthesis of four diastereomers, individually. The absolute stereochemistry was confirmed by X-ray crystal structure analysis of the corresponding tetraacetate of 1 by Prasad 11 also reported its total synthesis by using D-ribose and L-ascorbic acid as starting materials.…”

Metathetic Synthesis of Common and Medium-Sized Lactones: The State of the Art

“…Some RCM-based syntheses for this compound using both [147,148], synparvolide C 85 [149], and (À)-synrotolide 86 [150] are selected δ-lactones belonging to this group and recently prepared by a RCM reaction as the key step. Metathetic syntheses of lactones 81-86 are shown in Scheme 31.…”