136114-02-8Relevant academic research and scientific papers
Pyrolysis of lignin in the presence of tetramethylammonium hydroxide: a convenient method for S/G ratio determination.
Kuroda, Ken-ichi,Nishimura, Natsuno,Izumi, Akiko,Dimmel, Donald R
, p. 1022 - 1027 (2002)
Pyrolysis-gas chromatography in the presence of tetramethylammonium hydroxide (TMAH) was applied to the determination of the ratio of the abundances of the syringyl beta-aryl ether subunits to those of the guaiacyl equivalents (S/G) in lignin. Diazomethane-methylated kenafs (Hibiscus cannabinus and Hibiscus sabdariffa) and beech (Fagus crenata) in situ lignins were employed. Relative abundances of pyrolysis products derived from the guaiacyl and syringyl beta-aryl ether subunits were determined. The S/G ratios for in situ lignins were obtained with average 3.1% relative standard deviation for a minimum of six repeated runs. The S/G ratios determined by pyrolysis in the presence of TMAH agreed well with those determined by thioacidolysis, with a significant linear regression (R(2) = 0.9867). The results showed that pyrolysis with TMAH is an effective tool for obtaining information on the S/G ratio for in situ lignins.
Nickel-Catalyzed system for the cross-coupling of alkenyl methyl ethers with grignard reagents under mild conditions
Hostier, Thomas,Neouchy, Zeina,Ferey, Vincent,Gomez Pardo, Domingo,Cossy, Janine
supporting information, p. 1815 - 1818 (2018/04/14)
A nickel-catalyzed cross-coupling of alkenyl methyl ethers with Grignard reagents, under mild conditions, is described. These conditions allowed access to various stilbenes and heterocyclic stilbenic derivatives as well as to a potential anticancer agent DMU-212.
Synthesis of Substrates for Aldolase-Catalysed Reactions: A Comparison of Methods for the Synthesis of Substituted Phenylacetaldehydes
Al-Smadi, Derar,Enugala, Thilak Reddy,Norberg, Thomas,Kihlberg, Jan,Widersten, Mikael
supporting information, p. 1187 - 1190 (2018/03/26)
Methods for the synthesis of phenylacetaldehydes (oxidation, one-carbon chain extension) were compared by using the synthesis of 4-methoxyphenylacetaldehyde as a model example. Oxidations of 4-methoxyphenylethanol with activated DMSO (Swern oxidation) or manganese dioxide gave unsatisfactory results; whereas oxidation with 2-iodoxybenzoic acid (IBX) produced 4-methoxyphenylacetaldehyde in reasonable (75%) yield. However, Wittig-type one-carbon chain extension with methoxymethylene-triphenylphosphine followed by hydrolysis gave an excellent (81% overall) yield of 4-methoxyphenylacetaldehyde from 4-methoxybenzaldehyde (a cheap starting material). This approach was subsequently used to synthesise a set of 10 substituted phenylacetaldehydes in good to excellent yields.
Strategies for the construction of morphinan alkaloid AB-rings: Regioselective Friedel-Crafts-type cyclisations of γ-aryl-β-benzoylamido acids with asymmetrically substituted γ-aryl rings
Davies, Stephen G.,Goddard, Euan C.,Roberts, Paul M.,Russell, Angela J.,Smith, Andrew D.,Thomson, James E.,Withey, Jonathan M.
, p. 274 - 284 (2017/03/01)
The regioselectivity of the Friedel-Crafts-type cyclisation of a range of γ-aryl-β-benzoylamido acids, bearing oxy substituents at the C(3)- and C(4)-positions of the γ-aryl ring, has been investigated. In all of the cases examined (with 3,4-dimethoxy, 3,4-methylenedioxy and 3-hydroxy-4-methoxy substituents) the Lewis acid promoted cyclisation proceeds with exclusive regioselectivity for attack at the C(6)-position rather than at the C(2)-position, and furnishes the corresponding N- and O-protected 3-amino-6,7-dihydroxy-1-tetralone derivatives. This inherent regioselectivity can be overturned by the regioselective introduction of chlorine as a blocking group for the C(6)-position; subsequent Lewis acid promoted cyclisation then proceeds with exclusive regioselectivity for attack at the C(2)-position to deliver the corresponding N- and O-protected 3-amino-5-chloro-7,8-dihydroxy-1-tetralone derivative. These complementary cyclisation protocols represent useful methods for the preparation of these benzo-fused carbocyclic ring systems, which are the functionalised AB-rings of a range of morphinan alkaloids.
LITHIATION OF THE BENZENE RING IN THE PRESENCE OF ortho-ALKYL SUBSTITUENTS BEARING ONE OR TWO HETEROATOMS ON THE β-CARBON. A CONVENIENT SYNTHESIS OF MELLEIN AND KIGELIN
Napolitano, Elio,Morsani, Massimo,Fiaschi, Rita
, p. 249 - 255 (2007/10/02)
The title reaction can be successfully accomplished by proton-metal exchange with n-butyllithium, and the usually observed elimination to a styrene derivative suppressed, provided an appropriate combination of heteroatoms bound to the β-carbon of the alky
