- 3-Alkyl-3-hydroxyglutaric acids: A new class of hypocholesterolemic HMG CoA reductase inhibitors. 1
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Derivatives of 3-hydroxy-3-methylglutaric acid (HMG), a portion of the substrate for HMG CoA reductase, were prepared and tested for their inhibitory action against rat liver HMG CoA reductase and for their hypocholesterolemic activity. Structure-dependent competitive inhibition was observed. Optimal structures had a freee dicarboxylic acid with an alkyl group of 13-16 carbons at position 3. 3-n-Pentadecyl-3-hydroxyglutaric acid (IC50 = 50 μM) reduced serum cholesterol in the Triton-treated rat and HMG CoA reductase activity in the 20,25-diazacholesterol-treated rat.
- Baran,Laos,Langford,Miller,Jett,Taite,Rohrbacher
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- Control of β-Branching in Kalimantacin Biosynthesis: Application of 13C NMR to Polyketide Programming
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The presence of β-branches in the structure of polyketides that possess potent biological activity underpins the widespread importance of this structural feature. Kalimantacin is a polyketide antibiotic with selective activity against staphylococci, and its biosynthesis involves the unprecedented incorporation of three different and sequential β-branching modifications. We use purified single and multi-domain enzyme components of the kalimantacin biosynthetic machinery to address in vitro how the pattern of β-branching in kalimantacin is controlled. Robust discrimination of enzyme products required the development of a generalisable assay that takes advantage of 13C NMR of a single 13C label incorporated into key biosynthetic mimics combined with favourable dynamic properties of an acyl carrier protein. We report a previously unassigned modular enoyl-CoA hydratase (mECH) domain and the assembly of enzyme constructs and cascades that are able to generate each specific β-branch.
- Walker, Paul D.,Williams, Christopher,Weir, Angus N. M.,Wang, Luoyi,Crosby, John,Race, Paul R.,Simpson, Thomas J.,Willis, Christine L.,Crump, Matthew P.
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supporting information
p. 12446 - 12450
(2019/08/16)
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- Low catalyst loading in ring-closing metathesis reactions
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An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
- Kadyrov, Renat
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supporting information
p. 1002 - 1012
(2013/02/23)
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- Solvent- and catalyst-free gem-bisallylation of carboxylic acid derivatives with allylzinc bromide
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A rapid and efficient procedure for the solvent-free synthesis of gem-bisallylation products has been achieved by allylzinc bromide with carboxylic acid derivatives in the absence of any catalysts at room temperature.
- Wei, Yu-Juan,Ren, Heng,Wang, Jin-Xian
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p. 5697 - 5699
(2008/12/22)
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- An efficient of Grignard-type procedure for the preparation of gem-diallylated compound
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An efficient and a new procedure for the conversion of various carboxylic acid derivatives into the corresponding gem-diallylated compound under mild reaction condition has been developed. The triallylaluminum mediated Grignard-type addition of carboxylic acid derivative was utilized as a key operation to affect the transformation. The procedure is operationally simple, giving good to excellent product yields for a broad range of substrates. The chemoselectivity and regioselectivity of triallylaluminum were also demonstrated.
- Shen, Kao-Hsien,Kuo, Chun-Wei,Yao, Ching-Fa
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p. 6348 - 6351
(2008/02/12)
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- A rapid and convenient synthesis of homoallylic alcohols by the barbier-grignard reaction
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The use of the Barbier-Grignard reaction, where premixed allyl bromide and the carbonyl compound are added to magnesium in ether, is reported for the synthesis of homoallylic alcohols. This reaction provides good to excellent yields of most homoallylic alcohols with minimal formation of Wurtz coupling products.
- Sormunen, Grant J.,Lewis, David E.
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p. 3473 - 3480
(2007/10/03)
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- Metal zinc-promoted gem-bisallylation of acid chlorides with allyl chlorides in the presence of chlorotrimethylsilane
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Treatment of acid chlorides (2) with allyl chlorides (1) in the presence of zinc dust and a catalytic amount of chlorotrimethylsilane (TMSCl) in THF brought about highly facile and effective coupling to give the corresponding gem-bisallylation products, 4-hydroxy-penta-1,6-dienes (3), in good to excellent yields. These reactions are assumed to proceed through allylzinc intermediates generated in situ.
- Ishino, Yoshio,Mihara, Masatoshi,Kageyama, Manabu
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p. 6601 - 6604
(2007/10/03)
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- Allylation of esters promoted by metallic dysprosium in the presence of mercuric chloride
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In the presence of mercuric chloride, the reactions of esters with allyl bromide and metallic dysprosium in anhydrous THF give diallyl alkyl carbinols in good yields. When γ-butyrolactone is used as the substrate, the corresponding product is 4-allyl-6-heptene-1, 4-diol.
- Jia, Yu,Zhang, Mingfu,Tao, Fenggang,Zhou, Jingyao
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p. 2829 - 2835
(2007/10/03)
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- Organometallic-type reactions in aqueous media mediated by indium. Allylation of acyloyl-imidazoles and pyrazoles. Regioselective synthesis of β,γ-unsaturated ketones.
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Indium mediated coupling of allylic bromide with acyloyl-imidazoles or pyrazoles in aqueous media gives the corresponding tertiary alcohols or ketones in good yield. The reaction provides a facile regioselective synthesis of P,β,γ-unsaturated ketones and its usefulness is demonstrated by the synthesis of the monoterpene artemesia ketone.
- Bryan, Vernal J.,Chan, Tak-Hang
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p. 6493 - 6496
(2007/10/03)
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- Preparation of tertiary alcohols and γ-lactones from allylsilanes and anhydrides
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The TiCl4-mediated reaction of allyltrimethylsilane and anhydrides yields alkyldiallylcarbinols.In the case of the diallylsilane 1,8-bis(trimethylsilyl)octa-2,6-diene and cyclic anhydrides, spiro-lactones resulting from a gem-diallylation are obtained with high stereoselectivity. allylsilane / anhydride / dialkylation
- Pellissier, Helene,Wilmouth, Serge,Santelli, Maurice
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p. 637 - 642
(2007/10/02)
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- SYNTHETIC STUDIES ON NOGALAMYCIN CONGENERS ; TOTAL SYNTHESES OF (+)-NOGARENE, (+)-7-DEOXYNOGAROL, AND (+)-7-CON-O-METHYLNOGAROL
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According to the retrosynthetic perspective, the title total syntheses were accomplished by employing the regioselective Diels-Alder reactions of the (+)-naphthoquinone (5), the CDEF-ring system of nogalamycin congeners, with various structural types of dienes (8, 16, and 26).The highly functionalized dienes (16 and 26) incorporating all the functionalities present in the A-rings of (+)-7-deoxynogarol (3) and (+)-7-con-O-methylnogarol (2), were prepared efficiently by way of the 1,4-cyclohexadiene and 2-cyclohexanone derivatives (6 and 21), respectively.Reaction mechanism of the key Diels-Alder reaction was also discussed in terms of its stereoselectivity.
- Kawasaki, Motoji,Matsuda, Fuyuhiko,Terashima, Shiro
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p. 5727 - 5744
(2007/10/02)
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- SYNTHESIS OF SUBSTITUTED BENZENOIDS AND BIPHENYLS VIA DIELS-ALDER CYCLOADDITION OF 6-METHOXY-2-PYRONES
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A convenient synthesis of substituted 6-methoxy-2-pyrones from alkyl and aryl esters is described.These pyrones undergo Diels-Alder reactions with acetylenic dienophiles to provide an efficient route to polysubstituted benzoates, phthalates and biphenyls.
- Ahmed, Salman A.,Bardshiri, Esfandiar,Simpson, Thomas J.
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p. 1595 - 1596
(2007/10/02)
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- REACTIONS OF ?-ALLYL COMPLEXES OF Ti(III) WITH ALLYL, ALKYL, AND PROPARGYL ELECTROPHILES
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The reactions of the ?-allyl complexes of Ti(III) with allyl bromides lead to the production of a mixture of cross-coupling and homocoupling products.In the case of alkyl and propargyl halides the dehalogenation products are formed.The reaction of the ?-allyl complexes of Ti(III) with allyl acetates, allyl phenyl ethers, and allyl aryl sulfones are catalyzed by Pd(PPh3)4 and give cross-coupling or elimination products, depending on the structure of the initial substrate.
- Kasatkin, A. N.,Kulak, A. N.,Tolstikov, G. A.,Lomakina, S. I.
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p. 1875 - 1889
(2007/10/02)
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- A Convenient Synthesis of Isotopically Labelled Anthraquinones, Chrysophanol, Islandicin, and Emodin. Incorporation of Chrysophanol into Tajixanthone in Aspergillus variecolor
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Cycloaddition reactions of labelled 6-methoxy-3-methyl-2-pyrone (1) with naphthoquinones provide the common fungal anthraquinones, chrysophanol (2), islandicin (3), and emodin (4) suitably labelled for biosynthetic studies, as demonstrated by synthesis and incorporation of chrysophanol into the xanthone metabolite, tajixanthone (17) in Aspergillus variecolor.
- Ahmed, Salman A.,Bardshiri, Esfandiar,Simpson, Thomas J.
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p. 883 - 884
(2007/10/02)
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- A New Flexible Synthesis of (R,S)-Mevalonolactone
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By selective ozonolysis of the diene (5), a new synthesis of (R,S)-mevalonolactone (1a) has been developed, which can be adapted to other compounds related to (1a).This has been exemplified by the synthesis of the monodeuteriated triol (4d) and dideuteriated mevalonolactone (1d).
- Ferraboschi, Patrizia,Canevotti, Renato,Grisenti, Paride,Santaniello, Enzo
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p. 2301 - 2304
(2007/10/02)
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- ACTIVATION DU ZINC PAR LE TRIMETHYLCHLOROSILANE: PREPARATION D'ALCOOLS β-ETHYLENIQUES A PARTIR DE BROMURES α-ETHYLENIQUES, DE DERIVES CARBONYLES ET DE ZINC DANS L'ETHER.
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β-ethylenic alcohols can be prepared in ether from an α-ethylenic bromide, a carbonyl compound and zinc, provided the metal is previously activated by addition of a small amount of trimethylchlorosilane.
- Picotin, G.,Miginiac, Ph.
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p. 4551 - 4552
(2007/10/02)
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- γ-Substituted Secondary Organoalkaline Compounds and their Chlorinated Precursors: Synthetic Applications
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The preparation of γ-functionalised secondary organoalkaline metal compounds starting from methyl 3-chlorobutanoate (obtained by addition of hydrogen chloride to commercially available methyl trans-2-butenoate) is described.Reactions of these metallated compounds with suitable electrophilic reagents leads to a variety of tertiary alcohol derivatives.
- Barluenga, Jose,Florez, Josefa,Yus, Miguel
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p. 846 - 849
(2007/10/02)
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- Studies on a Synthesis of (RS)-Mevalonic Acid Lactone
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Full details of a high yielding synthesis of mevalonic acid lactone (1) which is of particular value in the preparation of 3- and/or 3'-labelled compounds are described.The key step, conversion of 3-hydroxy-3-methylpentane-1,5-dioic acid (3) into 3-hydroxy-3-methylpentane-1,5-dioic anhydride (4) using acetic anhydride, has been fully investigated, and an additional method using acetyl chloride and triethylamine is described.
- Bardshiri, Esfandiar,Simpson, Thomas J.,Scott, A. Ian,Shishido, Kozo
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p. 1765 - 1767
(2007/10/02)
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- Reinvestigation of a Synthesis of (R,S)-Mevalonolactone
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An n.m.r. study of the reaction of 3-hydroxy-3-methylpentane-1,5-dioic acid (5) with excess of acetic anhydride is described.It has shown that 3-hydroxy-3-methylpentane-1,5-dioic acid anhydride (2), previously described by Scott and Shishido as an intermediate in their synthesis of mevalonolactone, is formed only transiently, along with 3-acetoxy-3-methylpentane-1,5-dioic acid (6).Both intermediates eventually give 3-acetoxy-3-methylpentane-1,5-dioic acid anhydride (3).To obtain (R,S)-mevalonolactone, sodium borohydride reduction of 3-hydroxy-3-methylpentane-1,5-dioic acid anhydride (2), prepared from the diacid (5) and N,N-dicyclohexylcarbodi-imide, is shown to be better than reduction of 3-acetoxy-3-methylpentane-1,5-dioic acid anhydride (3).
- Lewer, Paul,MacMillan, Jake
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p. 1417 - 1420
(2007/10/02)
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- An Easy Synthesis of (RS)-Mevalonic Acid Lactone
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A high-yielding synthesis of mevalonic acid lactone is described which is of particular value in the preparation of 3' labelled compounds.
- Scott, A. Ian,Shishido, Kozo
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p. 400 - 401
(2007/10/02)
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