Access to Both Anomers of Pectenotoxin Spiroketals by Kinetic Spiroketalization

Pihko, Petri M.; Aho, Jatta E.

doi:10.1021/ol048321t

Cited by 44 publications

(24 citation statements)

References 26 publications

(13 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Following their synthesis of the nonanomeric (a,g)-spiroketal core of the pectenotoxins [ 47 ] the group of Pihko further explored the preparation of nonanomeric [6,5]-spiroketals through kinetic control in acid catalyzed spirocyclization reactions [ 48 ]. Treatment of mixed ketal-alcohols under acid catalysis led to the formation of the nonanomeric spiroketals if the acid was carefully tuned and in aqueous THF medium ( Scheme 18 ).…”

Section: Synthesis Of Naturally Occurring Nonanomeric [65]-spirokmentioning

confidence: 99%

Recent Synthetic Approaches Toward Non-anomeric Spiroketals in Natural Products

2008

View full text Add to dashboard Cite

Many natural products of biological interest contain [6,5]- and [6,6]-spiroketal moieties that can adopt various configurations, benefiting or not from anomeric conformation stabilizing effects. The spiroketal fragments are often important for the biological activity of the compounds containing them. Most stable spiroketal stereoisomers, including those benefiting from conformational anomeric effects (gauche conformers can be more stable than anti conformers because of a contra-steric stabilizing effect), are obtained easily under acidic conditions that permit acetal heterolysis (formation of tertiary oxycarbenium ion intermediates). The synthesis of less stable stereoisomers requires stereoselective acetal forming reactions that do not permit their equilibration with their most stable stereoisomers or, in the case of suitably substituted derivatives, concomitant reactions generating tricyclic products that quench the less stable spiroketal conformers. Ingenuous approaches have been recently developed for the synthesis of naturally occurring [6,6]- and [5,6]-nonanomeric spiroketals and analogues. The identification of several parameters that can influence the stereochemical outcome of spirocyclization processes has led to seminal improvements in the selective preparation of the non-anomeric isomers that are discussed herein. This review also gives an up-dated view of conformational anomeric effect which represents a small fraction of the enthalpic anomeric effect that makes gem-dioxy substituted compounds much more stable that their 1,n-dioxy substituted isomers (n > 1). Although models assuming sp3-hybridized oxygen atoms have been very popular (rabbit ears for the two non-bonding electron pairs of oxygen atom), sp2-hybridized oxygen atoms are used to describe the conformational anomeric effect.

show abstract

Section: Synthesis Of Naturally Occurring Nonanomeric [65]-spirokmentioning

confidence: 99%

Recent Synthetic Approaches Toward Non-anomeric Spiroketals in Natural Products

2008

View full text Add to dashboard Cite

show abstract

“…Key 1 H, 1 H COSY and HMBC correlations, in conjunction with the ACD/labs software, [4] established the position of the AB system (C7) in relation to the lactone ring and the spiroacetal carbon (C8). In turn the spiroacetal carbon (C8) initiated the connectivity and substitution of the tetrahydro- Table 1 [5] anomeric [6] over a [6.6]- [7] spiroketal system. The remaining correlations in the 1 H, 1 H COSY, HSQC and HMBC spectra ascribed the location of the hydroxyl substituted (C16) long chain alkyl group at position C13 of the tetrahydropyran ring (Figure 3).…”

Section: Introductionmentioning

confidence: 99%

Anticancer Agents from the Australian Tropical Rainforest: Spiroacetals EBC‐23, 24, 25, 72, 73, 75 and 76

Dong

Schill

Grange

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

EBC-23, 24, 25, 72, 73, 75 and 76 were isolated from the fruit of Cinnamomum laubatii (family Lauraceae) in the Australian tropical rainforests. EBC-23 (1) was synthesized stereoselectively, in nine linear steps in 8 % overall yield, to confirm the reported relative stereochemistry and determine the absolute stereochemistry. Key to the total synthesis was a series of Tietze-Smith linchpin reactions. The novel spiroacetal structural motif, exemplified by EBC-23 (1), was found to inhibit the growth of the androgen-independent prostate tumor cell line DU145 in the mouse model, indicating potential for the treatment of refractory solid tumors in adults.

show abstract

“…90 Less common, the PMB ether was a good protecting and leaving group during the acidpromoted synthesis of spiroketal units of pectenotoxin proposed by Pihko et al. 89 Unfortunately, no matter which the acid tested a mixture of kinetic and thermodynamic spiroketals is observed, with as a best result chloroacetic acid (49% yield with 5% of the epimer). …”

Section: Scheme 25: Thf Formation By Reductive Cyclizationmentioning

confidence: 99%

Recent advances in the synthesis of tetrahydrofurans and applications in total synthesis

et al. 2016

View full text Add to dashboard Cite

Mousseron. His research interests include the total synthesis of oxygenated cyclic and non cyclic metabolites of polyunsaturated fatty acids, mainly leukotrienes, iso-, phyto-and neuroprostanes, as well as dihydroxylated PUFAs and more recently lipophenols and the understanding of the role of such bioactive lipids and lipophenols by developing collaborations with chemists, biochemists, biologists and clinicians across the world. Jean-Marie Galano studied chemistry at Paul Cézanne Université Marseille and obtained his PhD under the supervision of Honoré Monti in 2001. He then moved to the University of Oxford to pursue a postdoctoral fellowship with David H. Hodgson on the development of new methods for the total synthesis of natural products. In October 2005 he joined the CNRS as a Chargé de Recherche at Université of Montpellier. His research focuses on the total synthesis and discovery of new lipid metabolites, and to discover their potential implications in human health. AbstractMany natural products contain tetrahydrofuran (THF) moieties. Those molecules, often biologically active, may be structurally diverse, e.g. cis or trans THF, mono-, di-, tri-or tetrasubstituted on the furan ring. Thus, the construction of THF is of great interest for the community of organic chemists; especially in developing new methodologies, and applying them in the total synthesis of natural products. The aim of this review is to report recent advances in the field of THF synthesis, as well as the application of these methods to the synthesis of bioactive compounds.

show abstract

Access to Both Anomers of Pectenotoxin Spiroketals by Kinetic Spiroketalization

Cited by 44 publications

References 26 publications

Recent Synthetic Approaches Toward Non-anomeric Spiroketals in Natural Products

Recent Synthetic Approaches Toward Non-anomeric Spiroketals in Natural Products

Anticancer Agents from the Australian Tropical Rainforest: Spiroacetals EBC‐23, 24, 25, 72, 73, 75 and 76

Recent advances in the synthesis of tetrahydrofurans and applications in total synthesis

Contact Info

Product

Resources

About