Stereoselective synthesis of six- and seven-membered ether rings based on the ring expansion

Nakata, Tadashi; Nomura, Sumihiro; Matsukura, Hiroko

doi:10.1016/0040-4039(95)02131-0

Cited by 57 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rearrangement of the five-and six-membered ethers 8a-10a having a mesylate as the leaving group at the C 1'-position on the side chain was examined (Scheme 2) (ref. 6). This type of rearrangement was first reported during the total synthesis of lasalocid A (ref.…”

Section: Synthetic Methods Of Cyclic Ether Ring Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Synthetic Study of Marine Polycyclic Ethers: Total Synthesis of Hemibrevetoxin B.

Nakata

1998

J. Syn. Org. Chem., Jpn.

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Synthetic Methods Of Cyclic Ether Ring Systemsmentioning

confidence: 99%

“…Recently, we have developed two efficient methods for the synthesis of the cyclic ethers (ref. 6,7) and have completed the stereoselective total synthesis of hemibrevetoxin B (2) based on the newly developed methods (ref. 8,9).…”

Section: Introductionmentioning

confidence: 99%

Synthetic Study of Marine Polycyclic Ethers: Total Synthesis of Hemibrevetoxin B.

Nakata

1998

J. Syn. Org. Chem., Jpn.

Self Cite

View full text Add to dashboard Cite

show abstract

“…[6] If this reaction were successful, we wanted to explore the role of a pendent (protected?) hydroxy group in trapping the cation and forming a spiroketal (6).…”

mentioning

confidence: 99%

“…[6] If this reaction were successful, we wanted to explore the role of a pendent (protected?) hydroxy group in trapping the cation and forming a spiroketal (6). [7] This sequence, which we called hydride-shift-initiated spiroketalization, would be another potentially general piece of methodology for organic synthesis.…”

mentioning

confidence: 99%

“…Interestingly, the absence of water and the presence of the polar solvent hexafluoroisopropanol (HFIPA) allowed a one-pot hydride shift, oxygen deprotection, and spiroketalization sequence to occur, forming 9 in 72 % yield (entry 2). Further studies showed that both TES and TBS protecting groups gave acceptable yields in the spiroketalization process (entry 3), and that the extra activation imparted by an a-chloromesylate group (Mc) [6] was essential to the success of the reaction (compare with entries 4 and 5). Our conclusion was that we had found the correct balance of protecting-group stability and leaving-group activation in this prototype, and that this new method of spiroketal formation was suitable for application in a more complex setting.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Interplay of Cascade Oxidative Cyclization and Hydride Shifts in the Synthesis of the ABC Spiroketal Ring System of Pectenotoxin‐4

Donohoe

Lipiński

2013

Angewandte Chemie

View full text Add to dashboard Cite

The pectenotoxins (PTXs) are a family of cyclic polyether macrolide toxins first isolated in 1985 by Yasumoto and coworkers from the digestive glands of scallops (Patinopecten yessoensis). [1] It has since been discovered that the producers of pectenotoxins are toxic plankton (Dinophysis dinoflagellate) found in many coastal areas around the world. To date, more than 20 members have been isolated and characterized, with structural variations commonly involving the configuration of the AB spiroketal (C7) as well as the oxidation state at C43. Recent studies have demonstrated that the pectenotoxins exhibit potent biological activity, including selective cytotoxicity against p53 mutant and p53-deficient tumors. [2] The exquisite architectural complexity of these 26-membered macrolactones, which consist of either 19 or 20 stereogenic centers embedded within three tetrahydrofuran rings, plus one spiroketal and one bicyclic ketal, poses a synthetic challenge that has attracted considerable attention from many research groups. While significant synthetic endeavors have been directed toward the pectenotoxins, [3] to date only one total synthesis of PTX-4 and PTX-8 has been reported. [4] In particular we were drawn to the C1-16 fragment of the pectenotoxins, because it contains a pair of THF rings terminating with a spiroketal unit that could be derived from a linear precursor; a synthesis would allow us to develop two concepts that should find general use in organic synthesis. Our first idea was to prepare a triol-containing linear diene, such as 1 (Scheme 1), and carry out an oxidative cyclization [5] in a cascade mode, catalyzed by osmium(VI). In the first instance, we might expect the vicinal diol unit in 1 to chelate to the osmium catalyst and facilitate an oxidative cyclization onto the trisubstituted alkene, thus forming a THF ring (2). The stereospecific (syn) addition of the two oxygen atoms across the alkene will ensure the correct configuration in the product. We then hoped that the metal chelate formed after cyclization would translocate onto the hydroxy group at C10 and thus enable a second oxidative cyclization onto the pendent C-6,7 alkene, forming 3 in the process. If successful, this method would expand the limits of the catalytic oxidative cyclization and form both THF rings of the target in one pot.Our second point of interest was the notion of using the exocyclic hydroxy group at C6 to initiate a hydride shift and form an oxo-carbenium ion in situ (see 4!5). [6] If this reaction were successful, we wanted to explore the role of a pendent (protected?) hydroxy group in trapping the cation and forming a spiroketal (6). [7] This sequence, which we called hydride-shift-initiated spiroketalization, would be another potentially general piece of methodology for organic synthesis.Initial results strongly suggested that the success of the hydride shift depended on the relative configuration between the exocyclic hydroxy group (activated as a leaving group) and the ring junction. [8] Moreover, previous experi...

show abstract

Methanesulfonyl Chloride

Vaillancourt¹,

Cudahy²,

Kreilein³

et al. 2007

Encyclopedia of Reagents for Organic Synthesis

View full text Add to dashboard Cite

Stereoselective synthesis of six- and seven-membered ether rings based on the ring expansion

Cited by 57 publications

References 27 publications

Synthetic Study of Marine Polycyclic Ethers: Total Synthesis of Hemibrevetoxin B.

Synthetic Study of Marine Polycyclic Ethers: Total Synthesis of Hemibrevetoxin B.

Interplay of Cascade Oxidative Cyclization and Hydride Shifts in the Synthesis of the ABC Spiroketal Ring System of Pectenotoxin‐4

Methanesulfonyl Chloride

Contact Info

Product

Resources

About