Synthesis of Nepetoidin B

Vitaliy Timokhin; Matthew Regner; Yukiko Tsuji; John Grabber; John Ralph

doi:10.1055/s-0036-1591556

Synthesis of Nepetoidin B

Synlett ◽

10.1055/s-0036-1591556 ◽

2018 ◽

Vol 29 (09) ◽

pp. 1229-1231 ◽

Cited By ~ 1

Author(s):

Vitaliy Timokhin ◽

Matthew Regner ◽

Yukiko Tsuji ◽

John Grabber ◽

John Ralph

Keyword(s):

Boron Tribromide ◽

Villiger Oxidation

The first synthesis of nepetoidin B in an overall yield of 17% was achieved in two steps through Baeyer–Villiger oxidation of commercially available 1,5-bis(3,4-dimethoxyphenyl)-1,4-pentadien-3-one with oxone to produce the tetramethylated nepetoidin B, followed by demethylation using boron tribromide.

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Synthesis of 8-Bromokalafungin as an Intermediate for the Preparation of C-Glycoside Derivatives

Australian Journal of Chemistry ◽

10.1071/c97018 ◽

1997 ◽

Vol 50 (7) ◽

pp. 711 ◽

Cited By ~ 4

Author(s):

Margaret A. Brimble ◽

Michael R. Nairn ◽

Hishani Prabaharan ◽

Nathan B. Walters

Keyword(s):

Cross Coupling ◽

Ceric Ammonium Nitrate ◽

Coupling Reactions ◽

Naphthalene Ring ◽

Fries Rearrangement ◽

Cross Coupling Reactions ◽

Oxidative Rearrangement ◽

Boron Tribromide ◽

Subsequent Addition ◽

Villiger Oxidation

The preparation of 8-bromokalafungin (20) which is a key intermediate for the synthesis of C-glycoside containing pyranonaphthoquinone antibiotics related to medermycin (6) is described. Although attempts to selectively monobrominate kalafungin (1) at C8 were unsuccessful, 8,10-dibromokalafungin (21) was prepared by using excess N-bromosuccinimide in chloroform. Selective bromination at C6 on a naphthalene ring was achieved upon treatment of naphthol (9) with N-bromosuccinimide (1 equiv.). Conversion of naphthol (9) into naphthoquinone (15) was effected by methylation, Baeyer–Villiger oxidation, acetylation via a Fries rearrangement and oxidation with ceric ammonium nitrate. Conversion of the 7-bromo quinone (15) into 8-bromokalafungin (20) proceeded through subsequent addition of 2-trimethylsilyloxyfuran (16) followed by oxidative rearrangement of the resultant furonaphthofuran (17) to furonaphthopyran (18). After reduction of the lactol (18) to cis ether (19), demethylation and epimerization at C5 with boron tribromide afforded 8-bromokalafungin (20). 8-Bromokalafungin (20) failed to undergo Pd(0)-mediated cross-coupling reactions with the stannyl glucal (22).

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Preparation and Characterization of Sn-β Zeolites by a Two-Step Postsynthesis Method and Their Catalytic Performance for Baeyer-Villiger Oxidation of Cyclohexanone

CHINESE JOURNAL OF CATALYSIS (CHINESE VERSION) ◽

10.3724/sp.j.1088.2012.11117 ◽

2013 ◽

Vol 33 (5) ◽

pp. 898-904 ◽

Cited By ~ 2

Author(s):

Zihua KANG ◽

Hai’ou LIU ◽

Xiongfu ZHANG

Keyword(s):

Catalytic Performance ◽

Villiger Oxidation

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Fluorinated tricyclic neuroleptics with prolonged action: 8-Methoxy, 8-ethoxy, 8-ethylthio and 8-hydroxy derivatives of 3-fluoro-10-(4-methylpiperazino)-10,11-dihydrodibenzo[b,f]thiepin

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821382 ◽

1982 ◽

Vol 47 (5) ◽

pp. 1382-1391 ◽

Cited By ~ 2

Author(s):

Jiří Jílek ◽

Josef Pomykáček ◽

Jiřina Metyšová ◽

Miroslav Protiva

Keyword(s):

Acetic Acid ◽

Polyphosphoric Acid ◽

Prolonged Action ◽

Substitution Reactions ◽

Methoxy Derivative ◽

Chloro Derivatives ◽

Boron Tribromide ◽

Derivatives Of ◽

Central Depressant ◽

Boiling Toluene

Acids IIa-c were prepared by reactions of (4-fluoro-2-iodophenyl)acetic acid with 4-methoxythiophenol, 4-ethoxythiophenol and 4-(ethylthio)thiophenol and cyclized with polyphosphoric acid in boiling toluene to dibenzo[b,f]thiepin-10(11H)-ones IIIa-c. Reduction with sodium borohydride afforded the alcohols IVa-c which were treated with hydrogen chloride and gave the chloro derivatives Va-c. Substitution reactions with 1-methylpiperazine resulted in the title compounds Ia-c out of which the methoxy derivative Ia was transformed by demethylation with boron tribromide to the phenol Id. Compounds Ia-d are very potent neuroleptics exhibiting a clear prolongation of the central depressant and some prolongation of the cataleptic activity.

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Reactivity of Sodium Hexaethyl-2,4-dicarba-nido-hexaborate(1-)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19990977 ◽

1999 ◽

Vol 64 (6) ◽

pp. 977-985 ◽

Cited By ~ 17

Author(s):

Bernd Wrackmeyer ◽

Hans-Jörg Schanz ◽

Wolfgang Milius ◽

Catherine McCammon

Keyword(s):

Mössbauer Spectroscopy ◽

Nmr Spectroscopy ◽

Structural Analysis ◽

Hydrogen Atom ◽

Mossbauer Spectroscopy ◽

Sandwich Complex ◽

X Ray ◽

Bromo Derivative ◽

Boron Tribromide ◽

C Nmr

Sodium hexaethyl-2,4-dicarba-nido-hexaborate(1-) (6), available from hexaethyl-2,4-dicarba- nido-hexaborane(8) (4) by deprotonation, reacts with deuterated methanol, CD3OD, to give back 4 without H/D exchange of the B-H-B hydrogen atom. The reaction of 6 with diethylboron chloride, Et2BCl, affords hexaethyl-2,4-dicarba-closo-hexaborane(6) (7), the first example of a peralkylated carborane of this type. In contrast, the reaction of 6 with boron tribromide, BBr3, leads mainly to 2,3,4,5,6,7-hexaethyl-2,4-dicarba-closo-heptaborane(7) (8), together with the corresponding 1-bromo derivative (9) and the closo-carborane 7 as side products. The reaction of two equivalents of 6 with FeCl2 gives the air-stable sandwich complex bis[hexaethyl-2,4-dicarba-nido-hexaborate(1-)]iron 10 which was characterised by X-ray structural analysis. All products were characterised by 1H, 11B and 13C NMR spectroscopy, and 57Fe Mössbauer spectroscopy was used to study 10.

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ChemInform Abstract: BAEYER-VILLIGER OXIDATION WITH BIS(TRIMETHYLSILYL) PEROXIDE (ME3SIOOSIME3) UNDER ASSISTANCE OF TIN(IV) CHLORIDE OR BORON FLUORIDE-ETHYL ETHER COMPLEX (BF3.OET2)

Chemischer Informationsdienst ◽

10.1002/chin.198343127 ◽

1983 ◽

Vol 14 (43) ◽

Author(s):

S. MATSUBARA ◽

K. TAKAI ◽

H. NOZAKI

Keyword(s):

Ethyl Ether ◽

Boron Fluoride ◽

Ether Complex ◽

Villiger Oxidation

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New (old) hydroxo complexes of platinum(II) as catalysts for the Baeyer-Villiger oxidation of ketones with hydrogen peroxide

Journal of Molecular Catalysis A Chemical ◽

10.1016/s1381-1169(96)00246-4 ◽

1997 ◽

Vol 117 (1-3) ◽

pp. 413-423 ◽

Cited By ~ 68

Author(s):

Giorgio Strukul ◽

Alessandra Varagnolo ◽

Francesco Pinna

Keyword(s):

Hydrogen Peroxide ◽

Hydroxo Complexes ◽

Villiger Oxidation

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Cloning, Expression, Characterization, and Biocatalytic Investigation of the 4-Hydroxyacetophenone Monooxygenase from Pseudomonas putida JD1

Applied and Environmental Microbiology ◽

10.1128/aem.02707-08 ◽

2009 ◽

Vol 75 (10) ◽

pp. 3106-3114 ◽

Cited By ~ 34

Author(s):

Jessica Rehdorf ◽

Christian L. Zimmer ◽

Uwe T. Bornscheuer

Keyword(s):

Pseudomonas Putida ◽

Open Reading Frames ◽

Gene Encoding ◽

Open Chain ◽

Aromatic Ketones ◽

Heteroaromatic Compounds ◽

Aliphatic Ketones ◽

Expression Characterization ◽

Reading Frames ◽

Villiger Oxidation

ABSTRACT While the number of available recombinant Baeyer-Villiger monooxygenases (BVMOs) has grown significantly over the last few years, there is still the demand for other BVMOs to expand the biocatalytic diversity. Most BVMOs that have been described are dedicated to convert efficiently cyclohexanone and related cyclic aliphatic ketones. To cover a broader range of substrate types and enantio- and/or regioselectivities, new BVMOs have to be discovered. The gene encoding a BVMO identified in Pseudomonas putida JD1 converting aromatic ketones (HAPMO; 4-hydroxyacetophenone monooxygenase) was amplified from genomic DNA using SiteFinding-PCR, cloned, and functionally expressed in Escherichia coli. Furthermore, four other open reading frames could be identified clustered around this HAPMO. It has been suggested that these proteins, including the HAPMO, might be involved in the degradation of 4-hydroxyacetophenone. Substrate specificity studies revealed that a large variety of other arylaliphatic ketones are also converted via Baeyer-Villiger oxidation into the corresponding esters, with preferences for para-substitutions at the aromatic ring. In addition, oxidation of aldehydes and some heteroaromatic compounds was observed. Cycloketones and open-chain ketones were not or poorly accepted, respectively. It was also found that this enzyme oxidizes aromatic ketones such as 3-phenyl-2-butanone with excellent enantioselectivity (E ≫100).

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