- Iron-catalyzed reductive dehydroxylation of benzylic alcohols using polymethylhydrosiloxane (PMHS)
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The combination of FeCl3 and PMHS is an efficient reducing system for the selective dehydroxylation of secondary benzylic alcohols, even in the presence of carbonyls, under very mild conditions. Georg Thieme Verlag Stuttgart · New York.
- Chan, Li Yan,Lim, Jazreel Seh Kai,Kim, Sunggak
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experimental part
p. 2862 - 2866
(2012/01/11)
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- Scope and limitations of lithium-ethylenediamine-THF-mediated cleavage at the α-position of aromatics: Deprotection of aryl methyl ethers and benzyl ethers under mild conditions
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The scope and limitation of lithium-ethylenediamine-THF-mediated reductive bond cleavage at the α-position of aromatics were examined. Very mild conditions such as lithium metal (5 equiv) and ethylenediamine (7 equiv) in oxygen-free THF were quite effective for the demethylation of aromatic ethers even at as low as -10°C. Allyl benzyl ethers were also deprotected under these conditions with very little change of the allylic alcohol moiety. Through this study, 2,6-dimethylbenzyl (m-xylylmethyl, MXM) group was developed as an alternative of benzyl group, which is readily cleavable under the above mentioned reductive conditions.
- Shindo, Takeyuki,Fukuyama, Yasuaki,Sugai, Takeshi
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p. 692 - 700
(2007/10/03)
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- Palladium catalyzed cross-coupling reaction of Grignard reagents with halobenzoic acids, halophenols and haloanilines
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Convenient syntheses of substituted benzoic acids, phenols and anilines have been achieved by using palladium catalyzed cross-coupling reactions between Grignard reagents and aryl halides containing carboxy, hydroxy and amino groups without a protection-deprotection sequence.
- Bumagin, Nikolai A.,Luzikova, Elena V.
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p. 271 - 273
(2007/10/03)
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- Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
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The alkylation of aromatic compounds with aldehydes and ketones in the presence of a variety of metal cation-exchanged montmorillonites (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+, Zn2+, H+, Na+) has been investigated. Al3+- and Zr4+-Monts are revealed to be effective as catalysts, while no reaction takes place with Na+-mont. Al3+-Mont-catalysed alkylation of phenol with several aldehydes produces mainly or almost solely the corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that with several ketones affords selectively the corresponding alkylphenols in moderate to good yields. The alkylation always occurs at the carbonyl carbon without any skeletal rearrangement and the kind of products depends much on the steric hindrance of an electrophilic intermediary carbocation. The alkylation of anisole, veratrole and p-cresol proceeds well, while that of toluene, benzene, chlorobenzene and nitrobenzene scarcely occurs.
- Tateiwa, Jun-Ichi,Hayama, Ei,Nishimura, Takahiro,Uemura, Sakae
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p. 1923 - 1928
(2007/10/03)
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- Preparation of diphenolics
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A process for the production of diphenolic compounds having a divalent bridge. A first disubstituted phenol is reacted with an aldehyde in the presence of a secondary amine and excess alcohol to form an ether intermediate. The ether intermediate is reacted with a phenol having an open ortho or para position to form a diphenolic.
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- RECHERCHES SUR LES SUBSTANCES MESOGENES-VIII; PREPARATION ET PROPERTIES MESOMORPHES DE SERIES ISOMETRIQUES
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The synthesis and the mesomorphic properties of various series of isometric mesogenic compounds are described.It is confirmed that isometric mesogenic molecules may be nematogenic and/or smectogenic according to the position of the polar rigid core.
- Malthete, Jacques,Canceill, Josette,Gabard, Jacqueline,Jacques, Jean
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p. 2815 - 2821
(2007/10/02)
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