- Two-photon controlled sol-gel condensation for the microfabrication of silica based microstructures. the role of photoacids and photobases
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Two-photon excitation of photobases is used to induce pH changes and control the condensation step of the sol-gel process at the focal point of a laser beam in a confocal configuration. This two-photon microfabrication process, which is usually used in th
- Kustra,Martin,Chateau,Lerouge,Monnereau,Andraud,Sitarz,Baldeck,Parola
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p. 46615 - 46620
(2017/10/16)
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- Direct Ruthenium-Catalyzed Hydrogenation of Carboxylic Acids to Alcohols
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The "green" reduction of carboxylic acids to alcohols is a challenging task in organic chemistry. Herein, we describe a general protocol for generation of alcohols by catalytic hydrogenation of carboxylic acids. Key to success is the use of a combination of Ru(acac)3, triphos and Lewis acids. The novel method showed broad substrate tolerance and a variety of aliphatic carboxylic acids including biomass-derived compounds can be smoothly reduced.
- Cui, Xinjiang,Li, Yuehui,Topf, Christoph,Junge, Kathrin,Beller, Matthias
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supporting information
p. 10596 - 10599
(2015/09/02)
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- The 9-xanthenylmethyl group: A novel photocleavable protecting group for amines
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The 9-xanthenylmethyl group has been investigated as a photocleavable protecting group for amines. Several amines, including two amino acids, were protected in good to very good yield. Irradiation of the protected substrates in neutral solution regenerated the starting amines in good to excellent yield.
- Du, Hong,Boyd, Mary K
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p. 6645 - 6647
(2007/10/03)
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- 2-substituted-(2SR)-2-amino-2-((1SR,2SR)-2-carboxycycloprop-1- yl)glycines as potent and selective antagonists of group II metabotropic glutamate receptors. 1. Effects of alkyl, arylalkyl, and diarylalkyl substitution
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In this paper, we describe the synthesis of a series of α-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxy-cyclopropylglycine (2, L-CCG 1). Incorporation of a substituent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a aeries of four isomers, i.e., two racemic diastereomers. We explored alkyl substitution, both normal and terminally branched; phenylalkyl and diphenylalkyl substitution; and a variety of aromatic and carbocyclic surrogates for phenyl. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin-stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. We found that while alkyl substitution provided no increase in affinity relative to 2, phenylethyl and diphenylethyl substitution, as in 105 and 109, respectively, were quite beneficial. The affinity of 109 was further enhanced when the two aromatic rings were joined by an oxygen or sulfur atom to form the tricyclic xanthylmethyl and thioxanthylmethyl amino acids 113 and 114, respectively. Amino acid 113, with an IC50 of 0.010 μM in the [3H]Glu binding assay, was 52-fold more potent than 2, whose IC50 was 0.47 μM.
- Ornstein, Paul L.,Bleisch, Thomas J.,Arnold, M. Brian,Wright, Rebecca A.,Johnson, Bryan G.,Schoepp, Darryle D.
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p. 346 - 357
(2007/10/03)
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- Amino acid protecting groups
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This invention relates to compounds of the formula a compound of the formula STR1 wherein X is O, CR7 R8, S or NR9 wherein R7 and R8 are independently hydrogen, or lower alkyl, and R9 is lower alkyl; n is 0 or 1; R1 and R2 are independently hydrogen, lower alkyl, monoorganosilyl, diorganosilyl, triorganosilyl, halogen, aryl, or nitro; R3 is hydrogen, lower alkyl, monoorganosilyl, diorganosilyl, triorganosilyl, halogen, 9-fluorenylalkyl, cycloalkyl, aryl or aralkyl; R4 and R5 are independently hydrogen, lower alkyl, or aryl or one of R4 and R5 is 9-fluorenyl; R6 is H or COZ wherein Z is an amino acid, a peptide residue or a leaving group; and with the provisos that when n is 0 and R3 is hydrogen, R1 and R2 are not hydrogen, halogen or nitro; that when n is 0 and R3 is lower alkyl, R1 and R2 are not hydrogen; and that when X is O or CR7 R8 wherein R7 and R8 are H, that R1, R2, R3, R4, R5, and R6 are not all simultaneously H. The compounds of the present invention are useful in peptide synthesis as blocking or protecting groups for reactive groups. The present invention is also directed to a method of protecting a reactive group of an organic molecule during a reaction which modifies a portion of the molecule other than the protected group.
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- GENERAL METHOD FOR THE PHOTOGENERATION OF BENZOLATED CATIONIC AND ANIONIC SYSTEMS IN AQUEOUS SOLUTION. TEST OF RELATIVE STABILITY OF THESE SYSTEMS IN THE EXCITED STATE.
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A general method for the photogeneration of dibenzolated carbocations and carbanions is described with the aim of testing the relative stability of these species as a function of number of pi-electrons in the excited state.
- Krogh, Erik,Wan, Peter
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p. 823 - 826
(2007/10/02)
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