Organocatalytic Site-Selective Acylation of 10-Deacetylbaccatin III

Yanagi, Masanori; Ninomiya, Ryo; Ueda, Y.; Furuta, Takumi; Yamada, Takeshi; Sunazuka, Toshiaki; Kawabata, Takeo

doi:10.1248/cpb.c16-00037

Cited by 14 publications

(13 citation statements)

References 24 publications

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“…As natural product 3 possesses a terminal glucopyranoside moiety, we envisaged that catalyst C1 would enable 4⁗-OH selective acylation, even in the presence of a total of eight free hydroxy groups. 42) Treatment of 3 with isobutyric anhydride in the presence of 10 mol% of 4-dimethylaminopyridine (DMAP) in CHCl 3 /tetrahydrofuran (THF) (9 : 1, v/v) at −60 °C gave 3⁗-O-acylate 4 as a major product with 97% site selectivity in 85% yield. This result indicated that C(3⁗)-OH had the highest intrinsic reactivity among the eight free hydroxy groups of 3 in CHCl 3 /THF (9 : 1, v/v) solution.…”

Section: Reviewmentioning

confidence: 99%

Site-Selective Molecular Transformation: Acylation of Hydroxy Groups and C–H Amination

Ueda

2021

Chem. Pharm. Bull.

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Control of site selectivity is an exciting direction for synthetic organic chemistry owing to the possibility of selective modification of multifunctionalized molecules, ultimately including biomacromolecules. In this review, our recent research related to site selectivity in two types of transformation, namely, the acylation of hydroxy groups and C-H amination, is summarized. Regarding the acylation of hydroxy groups, catalystcontrolled site selectivity enables unconventional retrosynthetic analysis, leading to efficient syntheses of sugar-related natural and unnatural products. Regarding C-H amination, the discovery of unprecedented reaction sites in intermolecular amination mediated by dirhodium nitrenes is described. The findings of this research demonstrate the power of site-selective transformation in the synthesis of a particular class of compounds.

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Section: Reviewmentioning

confidence: 99%

Site-Selective Molecular Transformation: Acylation of Hydroxy Groups and C–H Amination

Ueda

2021

Chem. Pharm. Bull.

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“…148 Upon reacting 99 with anhydrides in the presence of DMAP, a slight preference for C10-acylation to yield 101 was observed (Figure 19, entry 1). However, this inherent selectivity was reinforced through the use of catalyst 73 , which afforded a 93:7 ratio of 101:100 (Figure 19, entry 2).…”

Section: Group Transfer To Hydroxyl Groupsmentioning

confidence: 99%

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

2017

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The application of small molecules as catalysts for the diversification of natural product scaffolds is reviewed. Specifically, principles that relate to the selectivity challenges intrinsic to complex molecular scaffolds are summarized. The synthesis of analogs of natural products by this approach is then described as a quintessential “late-stage functionalization” exercise wherein natural products serve as the lead scaffolds. Given the historical application of enzymatic catalysts to the site-selective alteration of complex molecules, the focus of this review is on the recent studies of non-enzymatic catalysts. Reactions involving hydroxyl group derivatization with a variety of electrophilic reagents are discussed. C–H bond functionalizations that lead to oxidations, aminations, and halogenations are also presented. Several examples of site-selective olefin functionalizations and C–C bond formations are also included. Numerous classes of natural products have been subjected to these studies of site-selective alteration including polyketides, glycopeptides, terpenoids, macrolides, alkaloids, carbohydrates and others. What emerges is a platform for chemical remodeling of naturally occurring scaffolds that targets virtually all known chemical functionalities and microenvironments. However, challenges for the design of very broad classes of catalysts, with even broader selectivity demands (e.g., stereoselectivity, functional group selectivity, and site-selectivity) persist. Yet, a significant spectrum of powerful, catalytic alterations of complex natural products now exists such that expansion of scope seems inevitable. Several instances of biological activity assays of remodeled natural product derivatives are also presented. These reports may foreshadow further interdisciplinary impacts for catalytic remodeling of natural products, including contributions to SAR development, mode of action studies, and eventually medicinal chemistry.

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“…29) The amide oxygen of catalyst 6 acted as a Brøn-sted base to allow hydrogen bonding with the relatively acidic hydroxy group of the substrate, thus inducing selective acylation of the adjacent hydroxy group. We therefore considered that this catalyst may alter the selectivity of the acylation of compound 5.…”

Section: This Article Is Dedicated To Professor Satoshi ōMura In Celementioning

confidence: 99%

Organocatalytic Site-Selective Acylation of Avermectin B<sub>2a</sub>, a Unique Endectocidal Drug

Yamada

Suzuki

Hirose

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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The organocatalytic site-selective monoacylation of avermectin B 2a , an insecticidal and anti-parasitic drug, was accomplished. Although an acetylation of avermectin B 2a using a 4-dimethylaminopyridine (DMAP) as a catalyst gave poor site-selectivity, use of our organocatalyst increased site-selectivity of the acylation at the C-5-OH as well as the yield of monoacetate. This catalyst was also effective in other acylations. Interestingly, trihaloacetylation under same conditions gave poor site-selectivity. However, the use of an enantiomer of our organocatalyst provided the C-4″-O-trihaloacetyl avermectin B 2a with excellent siteselectivity. These results indicate that the site-selective acylation of avermectin B 2a can be controlled by the combination of a suitable organocatalyst and an acid anhydride.

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Organocatalytic Site-Selective Acylation of 10-Deacetylbaccatin III

Cited by 14 publications

References 24 publications

Site-Selective Molecular Transformation: Acylation of Hydroxy Groups and C–H Amination

Site-Selective Molecular Transformation: Acylation of Hydroxy Groups and C–H Amination

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

Organocatalytic Site-Selective Acylation of Avermectin B<sub>2a</sub>, a Unique Endectocidal Drug

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