Catalytic asymmetric allylic oxidation of cyclic olefins ocurrs for the first time in very high (94-99% ee) enantioselectivity using copper(I) complexes malonyl derived bisoxazolines and tert-butyl p-nitroperbenzoate giving allyl benzoates moderate yield. The copper complex, 15 mol %, was used acetonitrile at -20 degrees C over an extended period, 5-12 d, with excess olefin together one equivalent perester. S-esters were generated accord model proposed previously (S,S)-bisoxazoline ligand....

Chiral N-heterocyclic carbene ligands based on [2.2]paracyclophanes form complexes with rhodium. These catalysts can be used in the high-yielding and enantioselective asymmetric conjugate addition of arylboron compounds to cyclic acyclic enones (see scheme). Supporting information for this article is available WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z52679_s.pdf or from author. Please note: The publisher not responsible content functionality any supporting supplied by...

N,N-Bis-(2,6-diisopropylphenyl)dihydroimidazolium chloride with palladium(II) acetate (2 mol %) was used as catalyst, without added base, to efficiently cross couple aryl, vinyl, and alkyl boronates boronic acids aryldiazonium tetrafluoroborate substrates. The reactions were performed at 0 °C or rt, giving product in 2 4 h 80 90% yields for isolated materials. Diazonium ions, formed situ, also under these conditions.

[reaction: see text] Catalyst formed from N,N-bis(2,6-diisopropylphenyl)dihydroimidazolium chloride and palladium(II) acetate (2 mol %) was used, without added base, to efficiently produce Heck coupled products with olefins aryl diazonium tetrafluoroborate substrates. The reactions were performed at room temperature, giving product in 2-4 h 80-90% yields for isolated materials. Diazonium ions, situ directly anilines, also couple under these conditions.

Bulky phenanthracenyl imidazolium-derived carbene ligands were investigated for copper-free Sonogashira coupling with terminal acetylenes. Aryl bromides and iodides gave coupled products in excellent yields from the Pd(PPh3)2Cl2 complex potassium t-butoxide 18-crown-6 THF. A remarkable dependence on size of ligand was found. The highest obtained bulky 2,9-dicyclohexyl-10-phenanthryl 5.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Virtual ChemLab Project: A Realistic and Sophisticated Simulation of Organic Synthesis Qualitative AnalysisBrian F. Woodfield , Merritt B. Andrus Tricia Andersen Jordan Miller Bryon Simmons Richard Stanger Gregory L. Waddoups Melissa S. Moore Swan Rob Allen Greg Bodily View Author Information Department Chemistry Biochemistry, Brigham Young University, Provo, UT 84602 Center for Instructional Design, 84602Cite this: J. Chem. Educ. 2005, 82, 11,...

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTEfficient Synthesis of 1,1'-Binaphthyl and 2,2'-Bi-o-tolyl-2,2'-bis(oxazoline)s Preliminary Use for the Catalytic Asymmetric Allylic Oxidation CyclohexeneMerritt B. Andrus, Davoud Asgari, Joseph A. SclafaniView Author Information Purdue University, Department Chemistry, West Lafayette, Indiana 47907-1393 Cite this: J. Org. Chem. 1997, 62, 26, 9365–9368Publication Date (Web):December 1997Publication History Received24 July 1997Published online26...

The total synthesis of (+)-geldanamycin (GA), following a linear route, has been completed using demethylative quinone-forming reaction as the last step. Key steps include use two new asymmetric boron glycolate aldol reactions. To set anti-C11,12 hydroxymethoxy functionality, (S,S)-5,6-bis-4-methoxyphenyldioxanone 8 was used. Methylglycolate derived from norephedrine 5 C6,7 methoxyurethane stereochemistry. quinone formation step nitric acid gave non-natural o-quino-GA product 55 10:1 over...

The boron enolate of pyrone 2 undergoes asymmetric aldol reactions with aldehydes to give protected anti 1,2-diols 3. is readily available from trans stilbene using dihydroxylation. Yields for the reaction range 62 92% and selectivities 6:1 >20:1 isomers. Protection hydrogenolysis products can be used remove pyrone, giving differentially diol intermediates 12 that are amenable multistep synthesis.

Microcolin B, a potent new immunosuppressant isolated from blue-green alga Lyngbya majuscula off the Venezuelan coast, has been made using methyl-directed asymmetric hydrogenation reaction with rhodium on alumina catalyst lactone 4 for synthesis of key (R,R)-2,4-dimethyloctanoic acid fragment 1. A new, direct mixed imide formation was also developed production unusual prolylpyrrolen-2-one 2 portion microcolin. The pentafluorophenyl ester CBZ-proline 5 reacted lithium imidate lactam 6,...

[reaction: see text] A highly efficient catalytic borylation process with aryldiazonium ions was developed using a carbene-palladium catalyst formed in situ to give arylpinacolatoborane products. An X-ray structure for the N-heterocyclic complex, used as from bis(2,6-diisopropylphenyl)-4,5-dihydroimidazolium chloride, obtained without added base.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA useful new enantiomerically pure synthon from malic acid: chelation controlled activation as a route to regioselectivityGary E. Keck, Merritt B. Andrus, and Duane R. RomerCite this: J. Org. Chem. 1991, 56, 1, 417–420Publication Date (Print):January 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/jo00001a076https://doi.org/10.1021/jo00001a076research-articleACS PublicationsRequest...

Geldanamycin (GA), an antitumor Hsp90 inhibitor, was made for the first time by using oxidative demethylation reaction as final step. A biaryldioxanone auxiliary set anti C11−12 hydroxy-methoxy functionality and a methylglycolate based on norephedrine used syn C6−7 methoxy-urethane. p-Quinone-forming oxidants, CAN AgO, produced unusual aza-quinone product. Nitric acid gave GA from trimethoxy precursor in 55% yield 1:10 mixture with nonnatural o-quino-GA.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe mechanism of tin tetrachloride promoted additions allylstannanes to aldehydes: a response Denmark, Wilson, and WillsonGary E. Keck, Merritt B. Andrus, Stephen CastellinoCite this: J. Am. Chem. Soc. 1989, 111, 21, 8136–8141Publication Date (Print):October 1, 1989Publication History Published online1 May 2002Published inissue 1 October 1989https://pubs.acs.org/doi/10.1021/ja00203a012https://doi.org/10.1021/ja00203a012research-articleACS...

Human P-glycoprotein (Pgp) is as an ATP-dependent efflux pump for a variety of chemotherapeutic drugs. The aim this study to evaluate whether Pgp modulators can be engineered exhibit high-affinity binding using polyvalency. Five bivalent homodimeric polyenes based on stipiamide linked with polyethylene glycol ethers in the range 3-50 A were synthesized and quantitatively characterized their effect function. homodimers displaced [(125)I]iodoarylazidoprazoin (IAAP), analogue substrate...

The total synthesis of the farnesyltransferase inhibitor kurasoin A has been achieved using a novel asymmetric phase-transfer-catalyzed glycolate alkylation reaction. 2,5-Dimethoxyacetophenone 7 with cinchonidinium catalyst 9 (10 mol %) and hydroxide base pivaloyl benzyl bromide 8 provided S-alkylation product 10 in high yield (80−99%) excellent enantioselectivity. Baeyer−Villiger oxidation, Weinreb amide formation, Grignard addition to TES-ether 17 gave protected target. Lithium peroxide...