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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01 Jan 1991
TL;DR: For instance, double-bond rearrangement may occur when X is a halogen and the halogen acid produced by the reaction is not neutralized as it is formed by inclusion of a base as discussed by the authors.
Abstract: Organopalladium halides, acetates, triflates and similar derivatives lacking β sp3-bonded hydrogens generally react easily with unhindered alkenes to form new alkenes in which an original, vinyl hydrogen is replaced by the organic group of the palladium reactant. The reactions occur in solution. Other Group VIII metals are ineffective in bringing about this transformation in acceptable yields. In the palladium reaction the organopalladium(II) reactant is reduced to the zero valent state while the halide, acetate, triflate or other, initial anionic ligand is converted into the corresponding acid (equation 1). If alkyl groups are attached directly to the double-bond carbons, double-bond rearrangement may occur and allylically substituted products can be produced. Normally, substitution occurs before any double-bond rearrangement occurs in the reactant alkene and the substituent is placed on one of the initial double-bond carbons (equation 2). Rearrangement of the double bond along a hydrocarbon chain to positions more distant from the substituent than the allylic position is occasionally observed, most often when X is a halogen and the halogen acid produced by the reaction is not neutralized as it is formed by inclusion of a base.
101 citations
TL;DR: In this article, a novel N-doped carbon (CN) was prepared by the hydrothermal method using glucosamine hydrochloride as both carbon and nitrogen precursor, followed by a postsynthesis heat treatment.
Abstract: A novel N-doped carbon (CN) was prepared by the hydrothermal method using glucosamine hydrochloride as both carbon and nitrogen precursor, followed by a postsynthesis heat treatment. Pd@CN exhibited 9 times higher activity compared to that of commercial Pd@AC on hydrogenation of benzoic acid to cyclohexanecarboxylic acid. The influence of solvent and substituent were also investigated. Besides, the hydrogenations of various benzoic acids have been carried out over Pd@CN.
101 citations
TL;DR: An overview of the synthesis of branched-chain sugars can be found in this article, where the concepts related to the nucleophilic reactions of sugar oxiranes, aldol addition, and cyclization of dialdehydes with nitroalkanes are discussed.
Abstract: Publisher Summary This chapter provides an overview of the synthesis of branched-chain sugars. The naturally occurring, branched-chain sugars were classified as rare sugars until the 1960's, but the discovery of numerous new sugars as the glycosidic component of antibiotics during the past two decades has stimulated extensive research on their chemistry and biochemistry. Most of the branched sugars found in Nature have a polar substituent at the branching carbon-atom (Type A); tertiary alcohols are commonest, but some of them are in the form of a methyl ether, acetate, or cyclic carbonate and, in several instances, an amino or a nitro group is attached to the tertiary carbon atom. Diversity is observed in the branchings, but some of them are chemically interconvertible and also can be derived from a common intermediate. This chapter explains the concepts related to the nucleophilic reactions of sugar oxiranes, aldol addition, and cyclization of dialdehydes with nitroalkanes. It also presents a brief discussion on methyl-branched sugars and two-carbon-branched sugar.
100 citations
Patent•
30 Oct 1992
TL;DR: An anticoagulant agent which comprises, as an active ingredient, an aromatic amidine derivative represented by the following general formula (1) or a salt thereof: ##STR1## wherein the group represented by ##STR2## is a group selected from indolyl, benzofuranyl, benzothienyl, benzimidazolyls, benzoxazolyl and benzothiazolyl; X is a single bond, an oxygen atom, a sulfur atom or a carbonyl group; and Y is a saturated or unsaturated 5- or 6
Abstract: An anticoagulant agent which comprises, as an active ingredient, an aromatic amidine derivative represented by the following general formula (1) or a salt thereof: ##STR1## wherein the group represented by ##STR2## is a group selected from indolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, naphthyl, tetrahydronaphthyl and indanyl; X is a single bond, an oxygen atom, a sulfur atom or a carbonyl group; and Y is a saturated or unsaturated 5- or 6-membered heterocyclic moiety or cyclic hydrocarbon moiety optionally having a substituent group, an amino group optionally having a substituent group or an aminoalkyl group optionally having a substituent group. The inventive compound has a high anticoagulant capacity based on its excellent FXa inhibition activity.
100 citations
TL;DR: A series of acyclic α-carbomethoxy-α-diazoacetanilides with different N-substituents, 5a-k, was prepared and the rhodium(II) acetate catalyzed reactions studied as discussed by the authors.
Abstract: A series of acyclic α-carbomethoxy-α-diazoacetanilides with different N-substituents, 5a-k, was prepared and the rhodium(II) acetate catalyzed reactions studied. It was found that the rhodium carhenoid reaction with these compounds occurred only at the N-substituent; when the N-substituent is a propargyl group, rhodium carbenoid addition to the triple bond is favored, resulting, ultimately, in the formation of a bicyclic furan derivative 8. With an N-(tert-butyloxycarbonyl)methyl substituent, interception of the rhodium carhenoid by the ester carbonyl oxygen occurred preferentially to give, eventually, 1,4-oxazine derivatives 9 and 9'
100 citations