Expedient Synthesis of Potent Cannabinoid Receptor Agonist (−)-CP55,940

Itagaki, Noriaki; Sugahara, Tsutomu; Iwabuchi, Yoshiharu

doi:10.1021/ol051570c

Cited by 32 publications

(14 citation statements)

References 19 publications

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“…Indeed, although many methods are available for deprotecting ketals in the presence of acetals, prior to our method, no method has been reported that allows the deprotection of acetals in the presence of ketals. [41][42][43]113,114) We found that treatment of acetals with trialkylsilyl trifluoromethanesulfonate (R 3 SiOTf)-pyridine base such as collidine gave the parent carbonyl groups in high yields via pyridiniumtype salt intermediates such as collidinium salt. The characteristic points of our method are as follows: 1) The reaction is unprecedented in that acetals from aldehydes can be deprotected in the presence of ketal, and 2) The reaction proceeds under weakly basic conditions (Chart 43).…”

Section: Organic Reactions Using Pyridinium Salt Intermediatesmentioning

confidence: 99%

Development of New Innovative Synthetic Organic Chemistry Using Lone Pairs of Oxygen Atoms

Fujioka

2020

CHEMICAL & PHARMACEUTICAL BULLETIN

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Oxygen atoms have a lone pair of electrons, so they have high chelation ability, high nucleophilic ability, stabilizing ability of adjacent cations, and take a chelate or oxocarbenium ion structure with Lewis acids and metals. I took advantage of these properties to develop three new reactions, 1) asymmetric synthesis of chiral quaternary carbon centers, 2) asymmetric synthesis using acetal functions, and 3) organic chemistry using acetal-type reactive salt chemical species, and applied them to biologically active natural products synthesis. New reactions described here are all innovative and useful for natural products synthesis. In particular, the first asymmetric synthesis of fredericamycin A, and concise asymmetric synthesis of anthracycline antibiotics, scyphostatin, ()-Sch 642305, ()-stenine, clavolonine, ()-rubrenolide, ()-rubrynolide, ()-centrolobine, and decytospolide A and B, etc., are noteworthy. Furthermore, since reactions using acetaltype reactive salt chemical species allow the coexistence of functional groups that normally cannot coexist, the reactions using reactive salts have potential to change the retrosynthesis planned based on conventional reactions.

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Section: Organic Reactions Using Pyridinium Salt Intermediatesmentioning

confidence: 99%

Development of New Innovative Synthetic Organic Chemistry Using Lone Pairs of Oxygen Atoms

Fujioka

2020

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…In 2005, Iwabuchi and co‐workers reported an asymmetric intramolecular aldol reaction to construct [3. n .1]‐bicyclic compounds using proline‐derived organocatalysts , . They converted 1,7‐ketoaldehyde 4b to aldol 5b , bearing a tertiary stereocenter, via a highly enantioselective aldol reaction.…”

Section: Figurementioning

confidence: 99%

Asymmetric Construction of Vicinal Stereocenters Containing Quaternary and Tertiary Carbons: Application to the Formal Synthesis of (–)‐Chenopodene

et al. 2019

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A new strategy for the construction of vicinal stereocenters containing quaternary and tertiary carbons has been developed. The quaternary carbon center was constructed by an enantioselective intramolecular aldol reaction with an organocatalyst (Hua-cat), and a [3.3.1]-bicyclic compound was obtained in 81 % with 84 % ee. The absolute configuration of the bicyclic compound was determined by modified Mosher's [a]

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“…Also in 2005, Iwabuchi and co-workers [24] described an efficient catalyzed intramolecular aldolizationo f( C s )-symmetric keto-aldehyde 50 (Scheme 11)i nt he presence of organocatalysts 48 and 49.T he reactionp roceeded with high chemo-,d iastereo-a nd enantioselectivity at room temperature to give endo [3.3.1] bicyclic aldols 51 (Scheme 11). With the tetrabuyltammonium salt of trans-silyloxy-l-proline 48,e nantiomer (À)-51 was obtained.…”

Section: Silylether Derivativesmentioning

confidence: 99%

Organocatalysts Derived from Unnatural α‐Amino Acids: Scope and Applications

Agirre

Arrieta

Arrastia

et al. 2018

Chemistry An Asian Journal

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The organocatalytic properties of unnatural aamino acids are reviewed. Post-translational derivatives of natural a-aminoa cids include 4-hydroxy-l-proline and 4amino-l-proline scaffolds, and also prolineh omologues. The activity of synthetic unnatural a-amino acid-based organocatalysts, such as b-alkyl alanines, alanine-based phosphines, and tert-leucine derivatives, are reviewed herein. The orga-nocatalytic properties of unnatural monocyclic,b icyclic, and tricyclicproline derivatives are also reviewed. Severalfamilies of these organocatalystsp ermitthe efficient and stereoselective synthesis of complex natural products. Most of the reviewedo rganocatalysts accelerate the reported reactions through covalent interactions that raise the HOMO (enamine intermediates) or lower the LUMO (iminiumintermediates).Scheme1.Ageneral (simplified) mechanism of addition reactionsbye namine organocatalysis promoted by a-amino acid derivatives.[a] M.

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Expedient Synthesis of Potent Cannabinoid Receptor Agonist (−)-CP55,940

Abstract: [reaction: see text] A stereocontrolled synthesis of (-)-CP55,940, a potent cannabinoid receptor agonist, has been attained using a novel aldolization/retro-aldolization interconversion strategy, in which a temporarily generated chiral aldol motif plays essential roles.

Cited by 32 publications

References 19 publications

Development of New Innovative Synthetic Organic Chemistry Using Lone Pairs of Oxygen Atoms

Development of New Innovative Synthetic Organic Chemistry Using Lone Pairs of Oxygen Atoms

Asymmetric Construction of Vicinal Stereocenters Containing Quaternary and Tertiary Carbons: Application to the Formal Synthesis of (–)‐Chenopodene

Organocatalysts Derived from Unnatural α‐Amino Acids: Scope and Applications

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