scholarly journals Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen–Cope rearrangement

2015 ◽  
Vol 11 ◽  
pp. 1220-1225 ◽  
Author(s):  
Qinggang Mei ◽  
Chun Wang ◽  
Zhigang Zhao ◽  
Weicheng Yuan ◽  
Guolin Zhang
Keyword(s):  
Flavonoid Glycoside ◽  
Cope Rearrangement ◽  
Naturally Occurring ◽  
Key Steps

The hemisynthesis of the naturally occurring bioactive flavonoid glycoside icariin (1) has been accomplished in eleven steps with 7% overall yield from kaempferol. The 4′-OH methylation of kaempferol, the 8-prenylation of 3-O-methoxymethyl-4′-O-methyl-5-O-prenyl-7-O-benzylkaempferol (8) via para-Claisen–Cope rearrangement catalyzed by Eu(fod)3 in the presence of NaHCO3, and the glycosylation of icaritin (3) are the key steps.

scholarly journals Total Synthesis of Mycalisine B

Marine Drugs ◽  
2019 ◽  
Vol 17 (4) ◽  
pp. 226 ◽  
Author(s):  
Haixin Ding ◽  
Zhizhong Ruan ◽  
Peihao Kou ◽  
Xiangyou Dong ◽  
Jiang Bai ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Large Scale ◽  
Reaction Conditions ◽  
Naturally Occurring ◽  
Key Steps

The first total synthesis of the marine nucleoside Mycalisine B—a naturally occurring and structurally distinct 4,5-unsaturated 7-deazapurine nucleoside—has been accomplished in 10 linear steps with 27.5% overall yield from commercially available 1,2,3,5-tetra-O-acetyl-ribose and tetracyanoethylene. Key steps of the approach include: (1) I2 catalyzed acetonide formation from 1,2,3,5-tetra-O-acetylribose and acetone at large scale; (2) Vorbrüggen glycosylation using N4-benzoyl-5-cyano-6-bromo-7H-pyrrolo[2,3–d]pyrimidine as a nucleobase to avoid formation of N-3 isomer; (3) mild and scalable reaction conditions.

Total synthesis of zincophorin

2005 ◽  
Vol 77 (7) ◽  
pp. 1131-1137 ◽  
Author(s):  
Janine Cossy ◽  
Christophe Meyer ◽  
Magali Defosseux ◽  
Nicolas Blanchard
Keyword(s):  
Double Bond ◽  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Naturally Occurring ◽  
Key Steps ◽  
Stereogenic Center

A total synthesis of the naturally occurring ionophore zincophorin has been realized. The key steps are an intramolecular oxymercuration of a cyclopropanemethanol for the elaboration of the tetrahydropyran ring and a Carroll–Claisen rearrangement to control the configuration of the double bond at C20–C21 as well as the stereogenic center at C21.

scholarly journals Total Synthesis of Surinamensinols A and B

SynOpen ◽  
2020 ◽  
Vol 04 (04) ◽  
pp. 84-88
Author(s):  
Ahmed Al-Harrasi ◽  
Satya Kumar Avula ◽  
Biswanath Das ◽  
Rene Csuk ◽  
Ahmed Al-Rawahi
Keyword(s):  
Total Synthesis ◽  
Allyl Alcohol ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Ethyl Lactate ◽  
Naturally Occurring ◽  
Cross Coupling Reaction ◽  
Synthetic Sequence ◽  
Key Steps ◽  
Single Approach

AbstractAn efficient total synthesis of the naturally occurring anti-inflammatory and antitumour 8-O-4′-neolignans, surinamensinols A and B, has been accomplished from commercially available allyl alcohol and (S)-ethyl lactate. The synthetic sequence involves a palladium-catalysed Suzuki–Miyaura cross-coupling reaction followed by a chiral Mitsunobu­ reaction as the key steps. This is the first report of the simultaneous stereoselective total synthesis of surinamensinols A and B through a single approach involving only six steps.

The Synthesis of 5-Hydroxy-3-methylnaphtho[2,3-c]furan-4,9-dione and 5,8-Dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione

2003 ◽  
Vol 56 (7) ◽  
pp. 691 ◽  
Author(s):  
Matthew J. Piggott ◽  
Dieter Wege
Keyword(s):  
Furan Ring ◽  
Quinone Methide ◽  
Structural Representation ◽  
Naturally Occurring ◽  
Aloe Ferox ◽  
Key Steps ◽  
Derivatives Of

5-Hydroxy-3-methylnaphtho[2,3-c]furan-4,9-dione (1), a metabolite isolated from Aloe ferox and Bulbine capitata, has been synthesized by a sequence involving an annulation reaction between the anion of 4-methoxy-3-oxo-1,3-dihydroisobenzofuran-1-carbonitrile (8) and (E)-pent-3-en-2-one, followed by subsequent construction of the furan ring through allylic bromination, hydrolysis, and dehydration as the key steps. The formation of several unusual products observed in annulation reactions between (8) and O-protected derivatives of (E)-5-hydroxypent-3-en-2-one (9) can be rationalized by invoking the intermediacy of a reactive o-quinone methide. 5,8-Dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione (2), another naturally occurring naphtho[2,3-c]furan-4,9-dione, has been prepared by a Friedel–Crafts acylation of 1,4-dimethoxybenzene with 2-methylfuran-3,4-dicarbonyl dichloride. Arguments are presented that 5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione is a better structural representation than the alternative 4,9-dihydroxynaphtho[2,3-c]furan-5,8-dione tautomer in such systems, as the latter would contain a reactive isobenzofuran moiety.

Total Synthesis of Macaranin B

2021 ◽  
Author(s):  
Shintaro Matsumoto ◽  
Akio Aoyama ◽  
Shinnosuke Wakamori ◽  
Hidetoshi Yamada
Keyword(s):  
Total Synthesis ◽  
Michael Addition ◽  
Oxidative Coupling ◽  
Coupling Reaction ◽  
Oxidative Coupling Reaction ◽  
Naturally Occurring ◽  
Key Steps

Abstract This study describes the total synthesis of macaranin B, a naturally occurring ellagitannin containing 1-O-galloyl and 3,6-O-macaranoyl groups in an axial-rich D-glucose. The Key steps of the synthesis include an oxidative coupling reaction of galloyl groups with 1,2,4-orthoacetylglucose moiety and oxa-Michael addition/elimination using an orthoquinone monoketal. This facilitates the construction of the macaranoyl group and the first total synthesis of macaranin B.

scholarly journals Production of a Novel Quercetin Glycoside through Metabolic Engineering of Escherichia coli

2012 ◽  
Vol 78 (12) ◽  
pp. 4256-4262 ◽  
Author(s):  
Jeong-A Yoon ◽  
Bong-Gyu Kim ◽  
Woo Ju Lee ◽  
Yoongho Lim ◽  
Youhoon Chong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Wild Type Strain ◽  
Flavonoid Glycoside ◽  
Flavonoid Glycosides ◽  
Nucleotide Sugar ◽  
Content Type ◽  
E Coli ◽  
Naturally Occurring ◽  
Quercetin Glycoside ◽  
By Products

ABSTRACTMost flavonoids exist as sugar conjugates. Naturally occurring flavonoid sugar conjugates include glucose, galactose, glucuronide, rhamnose, xylose, and arabinose. These flavonoid glycosides have diverse physiological activities, depending on the type of sugar attached. To synthesize an unnatural flavonoid glycoside,Actinobacillus actinomycetemcomitansgenetll(encoding dTDP-6-deoxy-l-lyxo-4-hexulose reductase, which converts the endogenous nucleotide sugar dTDP-4-dehydro-6-deoxy-l-mannose to dTDP-6-deoxytalose) was introduced intoEscherichia coli. In addition, nucleotide-sugar dependent glycosyltransferases (UGTs) were screened to find a UGT that could use dTDP-6-deoxytalose. Supplementation of this engineered strain ofE. coliwith quercetin resulted in the production of quercetin-3-O-(6-deoxytalose). To increase the production of quercetin 3-O-(6-deoxytalose) by increasing the supplement of dTDP-6-deoxytalose inE. coli, we engineered nucleotide biosynthetic genes ofE. coli, such asgalU(UTP-glucose 1-phosphate uridyltransferase),rffA(dTDP-4-oxo-6-deoxy-d-glucose transaminase), and/orrfbD(dTDP-4-dehydrorahmnose reductase). The engineeredE. colistrain produced approximately 98 mg of quercetin 3-O-(6-deoxytalose)/liter, which is 7-fold more than that produced by the wild-type strain, and the by-products, quercetin 3-O-glucose and quercetin 3-O-rhamnose, were also significantly reduced.

Pathology of Bone Cells in Pigs with Experimental Turbinate Osteoporosis (Atrophic Rhinitis)

1971 ◽  
Vol 29 ◽  
pp. 304-305
Author(s):  
A. W. Fetter ◽  
C. C. Capen
Keyword(s):  
Mucous Membrane ◽  
Bone Cells ◽  
Atrophic Rhinitis ◽  
Infectious Agents ◽  
Metabolic Disturbances ◽  
Progressive Reduction ◽  
Naturally Occurring ◽  
Fundamental Cause ◽  
Osteocytic Osteolysis ◽  
Uncertain Etiology

Atrophic rhinitis in swine is a disease of uncertain etiology in which infectious agents, hereditary predisposition, and metabolic disturbances have been reported to be of primary etiologic importance. It shares many similarities, both clinically and pathologically, with ozena in man. The disease is characterized by deformity and reduction in volume of the nasal turbinates. The fundamental cause for the localized lesion of bone in the nasal turbinates has not been established. Reduced osteogenesis, increased resorption related to inflammation of the nasal mucous membrane, and excessive resorption due to osteocytic osteolysis stimulated by hyperparathyroidism have been suggested as possible pathogenetic mechanisms.The objectives of this investigation were to evaluate ultrastructurally bone cells in the nasal turbinates of pigs with experimentally induced atrophic rhinitis, and to compare these findings to those in control pigs of the same age and pigs with the naturally occurring disease, in order to define the fundamental lesion responsible for the progressive reduction in volume of the osseous core.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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