- Oxysterols: 27-hydroxycholesterol and its radiolabeled analog
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We describe a convenient and stereoselective route to the synthesis of 27-hydroxycholesterol. Also its radiolabeled analog, 22, 23 di [3H]-27-hydroxycholesterol with high specific radioactivity (55 Ci/mmol) was synthesized by this method. Julia
- D'Ambra, Thomas E.,Javitt, Norman B.,Lacy, James,Srinivasan, Puliyur,Warchol, Tadeusz
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p. 401 - 407
(2007/10/03)
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- Synthesis of (25R)-cholest-5-ene-3β,26-diol and its radiolabeled analog
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A new, convenient and stereoselective route to the synthesis of (25R)-cholest-5-ene-3β,26-diol (1) and its radiolabeled analog 4 is described. The key step is a Julia condensation of sulfone 6 with aldehyde 12 to furnish compound 13. Further reduction of
- D'Ambra, Thomas E.,Javitt, Norman B.,Nakanishi, Koji,Warchol, Tadeusz
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p. 3801 - 3804
(2007/10/03)
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- Total synthesis of (-)-ircinianin and (+)-wistarin
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(-)-Ircinianin (1), a cyclic furanosesterterpenetetronic acid isolated from a marine sponge (genus Ircinia), is synthesized in 17 steps from (S)-2-methylpropane-1,3-diol mono THP ether 10 and 3-furfural. The key step involves a NiCl2-CrCl2-mediated coupling reaction of iodotriene 9 with chiral aldehyde 8 in DMSO and subsequent intramolecular Diels-Alder reaction in one pot. Both reactions proceed very smoothly at room temperature and eventually give the cyclic product 30A possessing the desired cyclic skeleton of 1 in 60% yield. The structure of 30A is determined by X-ray crystallographic analysis. The stereochemistry of Diels-Alder reactions of 7A and another acyclic precursor 7B are discussed. The first total synthesis of (+)-wistarin (2) is accomplished in 55% yield by iodoether ring formation of 1 and hydrogenolysis of the iodide 33A. Based on the coupling constant in the proton NMR spectrum of 33A, the reported structure 2A is revised to 2B.
- Uenishi, Jun'ichi,Kawahama, Reiko,Yonemitsu, Osamu
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p. 1691 - 1701
(2007/10/03)
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- The synthesis and biochemical pharmacology of enantiomerically pure methylated oxotremorine derivatives
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Previous pharmacological studies of methylated oxotremorine derivatives bearing substituents at the 3-, 4-, and 5-positions of the pyrrolidinone ring have been conducted using racemic mixtures, and not with optically active compounds. The synthesis and radioligand binding data of optically active, methylated oxotremorine derivatives at the 3- and 4-positions are described. There are significant pharmacological differences between the 3- and 4- position derivatives. The 4-position enantiomers have weak, approximately equal affinity and antagonist-like profiles, whereas the 3-position enantiomers have significantly different affinities and partial agonist-like profiles.
- Trybulski,Zhang,Kramss,Mangano
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p. 3533 - 3541
(2007/10/02)
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- On the Mechanism of Lewis Acid Promoted Ene Cyclizations of ω-Unsaturated Aldehydes
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The diastereomerically labeled d1 enals 1 and 2 were prepared from (S)-3-bromo-2-methylpropanol 5 by a sequence involving homologation to the allylic alcohol 13 and Sharpless epoxidation to either the α- or the β-epoxide diastereomers 14 or 15.Reduction w
- Marshall, James A.,Andersen, Marc W.
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p. 5851 - 5856
(2007/10/02)
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- REVISION OF THE ABSOLUTE CONFIGURATION OF A-FACTOR; THE INDUCER OF STREPTOMYCIN BIOSYNTHESIS, BASING ON THE RECONFIRMED (R)-CONFIGURATION OF (+)-PARACONIC ACID
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(+)-Paraconic acid was shown to be of (R)-configuration by its four-step conversion to (R)-(+)-3-methyl-4-butanolide.The absolute configuration at C-3 of A-factor was therefore revised to be R, since it was synthesized from (S)-(-)-paraconic acid.
- Mori, Kenji
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p. 3107 - 3109
(2007/10/02)
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