Topic
Substituent
About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.
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TL;DR: In this paper, a structure-activity series was produced by varying the substituent at C-7 on the aromatic ring [R=MeO, t-BU, Me, H, Cl, F, CO 2 Me], which suggests that reduction occurs by direct attack of thiolate on the hydroxamic nitrogen of a resonance-stabilized ion pair.
Abstract: Analogues of the aglucones of naturally occurring cyclic hydroxamic acids (2,4-dihydroxy-1,4-benzoxazin-3-ones) from Gramineae (Poaceae) have been synthesized by the reductive cyclization of the ring-substituted methyl α-(o-nitrophenoxy)-α-methoxyacetates, followed by demethylation of the C-2 methoxy group with BBr 3 or BCl 3 to reveal the 2-hydroxy group. A structure-activity series was produced by varying the substituent at C-7 on the aromatic ring [R=MeO, t-BU, Me, H, Cl, F, CO 2 Me]. The remarkable rate enhancement provided by an oxa functionality suggests that reduction occurs by direct attack of thiolate on the hydroxamic nitrogen of a resonance-stabilized ion pair
85 citations
Patent•
02 Apr 1996
TL;DR: In this paper, the indole derivatives of formula (I) were introduced, where R?1 and R2 represent a 4-to 7-membered carboxylic ring optionally substituted with oxo, or its pharmaceutically acceptable salt.
Abstract: This invention relates to new indole derivatives of formula (I), wherein R1 is hydrogen, halogen, nitro, carboxy, protected carboxy, acyl, etc., R2 is hydrogen, halogen, lower alkenyl, acyl, etc., R3 is lower alkenyl or lower alkyl, both of which are optionally substituted with aryl optionally substituted with one or more substituent(s) selected from the group consisting of halogen, aryl, lower alkoxy, etc., and R4 is carboxy, protected carboxy, acyl, etc., in addition to their significances above, R?1 and R2?, together with the carbon atoms to which they are attached, represent a 4- to 7-membered carboxylic ring optionally substituted with oxo, or its pharmaceutically acceptable salt, which is useful as a medicament; and to new use of cyclic nucleotide-PDE inhibitors.
85 citations
TL;DR: A tandem 1,5-hydrogen atom transfer/radical oxidation/nucleophilic cyclization mechanism is proposed for the intramolecular hydrogen abstraction reaction promoted for primary carboxamidyl radicals.
85 citations
85 citations
TL;DR: In this article, the synthesis and optical properties of a series of anthracenyl-o-carborane dyads exhibiting highly-efficient luminescence with various types of substituent groups at the adjacent carbon atom of o-Carborane were described.
Abstract: This manuscript describes the synthesis and optical properties of a series of anthracenyl-o-carborane dyads exhibiting highly-efficient luminescence with various types of substituent groups at the adjacent carbon atom of o-carborane The restricted rotational motion of the anthracene moiety and the ideal orientation for intramolecular charge transfer from the anthracene moiety to the carborane cluster resulted in yellow and orange emissions (λem = 563 nm and 604 nm) with approximately 100% absolute fluorescence quantum efficiencies in the crystalline state of the methyl- and trimethylsilyl (TMS)-substituted dyads, respectively In additional, clear thermochromic luminescence properties were also observed Computer calculations were carried out to investigate the influence of the substituent effect on emission efficiency
85 citations