- Diastereoselective Solid-Phase Synthesis of Novel Hydantoin- and Isoxazoline-Containing Heterocycles
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Exploiting 1,3-dipolar cycloaddition and carbanilide cyclization transformations, we have prepared novel spirocyclic isoxazoloimidazolidinedione heterocycles of generalized structures II and III on solid phase starting from Merrifield resin. Cyclopentanoid isoxazoloimidazolidinedione II was obtained with complete diastereoselectivity, and cyclopropanoid isoxazoloimidazolidinedione III was obtained as an ≈ 2:1 mixture of diastereomers.
- Park, Kyung-Ho,Olmstead, Marilyn M.,Kurth, Mark J.
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- Synthesis, Radiolabeling, and Biological Evaluation of the cis Stereoisomers of 1-Amino-3-Fluoro-4-(fluoro-18F)Cyclopentane-1-Carboxylic Acid as PET Imaging Agents
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The non-natural cyclic amino acids (1S,3R,4S)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid ([18F]9) and (1S,3S,4R)-1-amino-3-fluoro-4-(fluoro-18F)cyclopentane-1-carboxylic acid ([18F]28) have been prepared in 10 and 1.7% decay corrected radiochemical yield, respectively, and in greater than 99% radiochemical purity. Cell assays in rat 9L gliosarcoma, human U87 ΔEGFR glioblastoma, and human DU145 androgen-independent prostate carcinoma tumor cells indicated that both compounds are substrates for amino acid transport primarily by system L, with some transport taking place via system ASC. In rats with 9L gliosarcoma, [18F]9 and [18F]28 provided high tumor to normal brain tissue ratios, with maximal ratios of 3.5 and 4.1, respectively. Biodistribution studies in healthy rats confirmed that both compounds are BBB permeable and that bladder accumulation is low until at least 5 min post injection.
- Pickel, Thomas C.,Voll, Ronald J.,Yu, Weiping,Wang, Zhaobin,Nye, Jonathon A,Bacsa, John,Olson, Jeffrey J.,Liebeskind, Lanny S.,Goodman, Mark M.
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p. 12008 - 12022
(2020/12/01)
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- Complete facial selectivity in the Diels-Alder reaction of a 5-amino-5-carboxycyclopentadiene derivative
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5-tert-Butoxycarbonylamino-5-carbethoxy-2-tert-butyldimethylsilyloxy- cyclopentadiene undergoes a Diels-Alder reaction exclusively from the face syn to the nitrogen functionality. Complete reversal of facial bias may be achieved, but at the cost of dimini
- Kim, Simon,Ciufolini, Marco A.
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supporting information; scheme or table
p. 3274 - 3277
(2011/08/05)
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- Microwave assisted synthesis of spiro-2,5-diketopiperazines
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A general and efficient method for the synthesis of spiro-2,5-diketopiperazines (spiro-DKPs) is described. Cyclization of Boc-protected dipeptides containing spiro-amino acids by microwave assisted heating in water furnished the corresponding spiro-DKPs. The spiro-amino acids were prepared by combining stereoselective alkylation reactions using the Sch?llkopf methodology for amino acid construction with Grubbs ring-closing metathesis (RCM) methodology using ruthenium complexes. The RCM reactions and all subsequent transformations to the spiro-DKPs were run with microwave assisted heating, resulting in high yields and short reaction times for all steps.
- Jam, Fariba,Tullberg, Marcus,Luthman, Kristina,Gr?tli, Morten
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p. 9881 - 9889
(2008/02/11)
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- Regio- and diastereoselective synthesis of cyclic amino esters
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Several cyclic amino esters have been prepared regio- and diastereoselectively depending on the electrophile (cis or trans alkene) and its leaving group.
- Park, Kyung-Ho,Kurth, Thomas M.,Olmstead, Marilyn M.,Kurth, Mark J.
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p. 991 - 992
(2007/10/03)
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- Diastereoselective synthesis of cyclopentanoids with hydantoin and isoxazoline substituents
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Exploiting 1,3-dipolar cycloaddition and urea → hydantoin cyclization transformations, novel spiro-[cyclopenta[d]isoxazole-4'5-imidazolindine' heterocycles of generalized structure I have been prepared. The 1-amino-3- cyclopentenecarboxylate precursor II was prepared from a suitably activated/protected derivative of glycine and the bis-alkylating agent cis- 1,4-dichloro-2-butene.
- Park, Kyung-Ho,Olmstead, Marilyn M.,Kurth, Mark J.
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p. 113 - 117
(2007/10/03)
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- Cyclit-Reaktionen, II. Darstellung von Bausteinen zur Synthese carbocyclischer Furanose-Analoga
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The four isomeric hydroxycyclopentenmethanols 6a to 9a can easily be made by allylhydroxylation of the epoxides 2 and 4 with phenyl selenide.In a second way the pair 8a and 9a has been synthesized from 11 via 15.As the preparation of 20 demonstrates, the functionalisation of 6a to 9a to carbocyclic furanoses is possible.The dicarboxylic diethyl esters 23 and 33 can be converted into models for carbocyclic ketofuranoses.
- Paulsen, Hans,Maass, Uwe
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p. 346 - 358
(2007/10/02)
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