Preparation of ortho-hydroxyalkylanilines as ortho-quinone methide imine precursors via an aminoborane complex

1995 ◽  
Vol 73 (9) ◽  
pp. 1506-1513 ◽  
Author(s):  
David Migneault ◽  
Michael A. Bernstein ◽  
Cheuk K. Lau
Keyword(s):  
Good Yield ◽  
Cycloaddition Reaction ◽  
Quinone Methide ◽  
Aliphatic Aldehydes ◽  
General Process ◽  
Aryl Aldehydes

A general process for ortho-specific hydroxyalkylation of secondary anilines has been developed. N-Methylanilinochlorophenylboranes react readily with aryl aldehydes, and with α,β-unsaturated or saturated aliphatic aldehydes to give the corresponding ortho-hydroxyalkylanilines in good yield. Thermolysis of the latter generated the corresponding ortho-quinone methide imine, which can participate in an electrocyclic or intramolecular [4 + 2] cycloaddition reaction to give various dihydro- and tetrahydroquinoline derivatives. Application of the method to the syntheses of 5-aza analogs of hexahydrocannabinol is demonstrated. Keywords: quinone methide imine, ortho-hydroxyalkylaniline, azacannabinoids.

Gold-catalyzed generation of vinylthionium ions and the development of an organocatalytic, asymmetric (4+3)-cycloaddition reaction

2017 ◽  
Author(s):  
◽  
Michael Topinka
Keyword(s):  
Amino Alcohol ◽  
Good Yield ◽  
Lewis Acids ◽  
Cycloaddition Reaction ◽  
Unsaturated Ester ◽  
Cycloaddition Reactions ◽  
University Of Missouri ◽  
Considerable Problem ◽  
The University ◽  
Substituted Furans

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] An allylic benzoate ester was prepared and used as a progenitor of vinylthionium ions for (4+3)-cycloaddition reactions. The chemistry was limited to 2-substituted and 2,5-disubstituted furans. In the case of 2-substituted furans, only Friedel-Crafts alkylation products were procured. In the case of 2,5-disubstituted furans, (4+3)-cycloaddition products were furnished in good yield. A catalytic, asymmetric variant using 2,5-dialkylfurans and chiral acids to procure cycloaddition products was unsuccessful. There was an opportunity to overcome the Friedel-Crafts alkylation problem that arose in a gold-catalyzed cycloaddition project. A sulfur-substituted unsaturated ester and alcohol were prepared, but silyl migration was a considerable problem upon activation by various agents. The problem of silyl migration was circumvented, but the target aldehyde was unreactive toward dienes in the presence of various Lewis acids. In further pursuit of an asymmetric (4+3)-cycloaddition reaction, 2-substituted furans were reacted with 2-tosyloxycyclopentanone in the presence of K2HPO4/H2O in perfluorobenzene as solvent and 30 mol% of an amino alcohol catalyst developed by David MacMillan. Enantioselectivities were modest for 2-alkylfurans and excellent for 2-arylchalcogenofurans (90% ee). 3-Substituted furans also work in this process.

RÉACTION DU SULFURE DE BORE AVEC QUELQUES GROUPES CARBONYLES

1964 ◽  
Vol 42 (8) ◽  
pp. 1928-1935 ◽  
Author(s):  
S. Jerumanis ◽  
J. M. Lalancette
Keyword(s):  
Good Yield ◽  
Aromatic Aldehydes ◽  
Methyl Benzoate ◽  
Active Hydrogen ◽  
Aliphatic Aldehydes ◽  
Inert Substance

The reactions of boron sulphide with some types of carbonyls have been studied. The reaction of boron sulphide with aromatic aldehydes and aliphatic aldehydes which have been deprived of active hydrogen in the α position gives a good yield of the corresponding trithioaldehydes. This reaction is examined for four aldehydes, namely, benzaldehyde, 3-methylbenzaldehyde, 3-nitrobenzaldehyde, and 2,2′-dimethylpropionaldehyde. Through this study the authors have brought out a method which enables either the α-trithiobenzaldehyde, m.p. 166–167 °C, or the β-trithiobenzaldehyde, m.p. 225–226 °C, to be obtained selectively. The reaction of 3-methylbenzaldehyde with boron sulphide yields only one β stereoisomer, but nitrobenzaldehyde remains completely inert. The aldehydes having one active hydrogen in the α position undergo a dehydrogenation at the same time as the oxygen is being replaced by one atom of sulphur. 2,2′-Dimethylthiopropanal exists in a trimeric state at normal temperatures and becomes monomeric at higher temperatures, whereas the trithiobenzaldehydes do not depolymerize. Methyl benzoate reacts with boron sulphide to give tetraphenyldioxadiene. The structure of this extremely inert substance has been established mainly by physical means: infrared, ultraviolet, and n.m.r. spectra. The reaction of benzophenone and acetophenone with boron sulphide has been investigated. The former has been found inert to the action of the sulphide, and the latter reacts quite readily to give 2,4-diphenylthiophene. The structure of this thiophene is established by desulphuration over nickel. The role of boron sulphide as dehydrogenating and deoxygenating agent is discussed, and a laboratory preparation of boron sulphide is described.

Asymmetric Hydrocyanation of a Range of Aromatic and Aliphatic Aldehydes

1988 ◽  
Vol 41 (11) ◽  
pp. 1697 ◽  
Author(s):  
BR Matthews ◽  
WR Jackson ◽  
GS Jayatilake ◽  
C Wilshire ◽  
HA Jacobs
Keyword(s):  
Hydrogen Cyanide ◽  
Enantiomeric Excess ◽  
Basic Catalyst ◽  
Strong Electron ◽  
Aliphatic Aldehydes ◽  
Aryl Aldehydes ◽  
Heterocyclic Aldehydes ◽  
Electron Withdrawing Substituents

A range of aryl, alkyl and heterocyclic aldehydes have been treated with hydrogen cyanide in the presence of the 'Inoue' catalyst, (R,R)- or (S,S)-cyclo [phenylalanylhistidyl]. Most aryl aldehydes with electron-donating substituents in the m- or p-positions give high enantiomeric excess (e.e.) values (≥80%) but aryl aldehydes with strong electron-withdrawing substituents gave moderate e.e. values (≤50%). These moderate values are believed to be due to partial racemization of the product cyanohydrins in the presence of the mildly basic catalyst. In contrast to the reactions of aryl aldehydes , reactions of alkyl aldehydes and of ketones gave low e.e. values (≤30%) and an explanation is proposed.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 868-874
Author(s):  
Maike Fischer ◽  
Yijian Shi ◽  
Bao-ping Zhao ◽  
Victor Snieckus ◽  
Peter Wan
Keyword(s):  
Aqueous Solution ◽  
Vinyl Ether ◽  
Hydroxy Group ◽  
Ground State ◽  
Cycloaddition Reaction ◽  
Quinone Methide ◽  
Quantum Yields ◽  
Ethyl Vinyl Ether ◽  
High Chemical ◽  
Ethyl Vinyl

The photosolvolysis of 1- and 2-hydroxy-9-fluorenols 4-6 has been studied in aqueous solution. All of these 9-fluorenols photosolvolyze efficiently in 1:1 H2O-CH3OH, to give the corresponding methyl ether products in high chemical and quantum yields. Whereas the photosolvolysis of the parent 9-fluorenol (2, R = H) is known to proceed via the very short-lived and formally ground-state antiaromatic 9-fluorenyl cation (1, R = H), the photosolvolysis of 1-hydroxy-9-fluorenol (4) proceeds via a much longer-lived (approximately = 5-10 s) fluorenyl quinone methide 9, which is trappable by ethyl vinyl ether via a [4+2] cycloaddition reaction to give a chroman derivative. Interestingly, 2-hydroxy-9-fluorenol (5) photosolvolyzes via a very short-lived intermediate with similar lifetimes as observed for the 9-fluorenyl cation (1, R = H), although a corresponding fluorenyl quinone methide intermediate is accessible for this compound. This study demonstrates that the mechanism of photosolvolysis of these types of compounds can be dramatically altered when an aryl hydroxy group is present.Key words: photosolvolysis, 9-fluorenyl cation, quinone methide, carbocation, antiaromatic.

scholarly journals Cu(I) Catalyzed Coumarin-1,2,3-Triazole Hybrids: Click Chemistry

2019 ◽  
Vol 31 (11) ◽  
pp. 2543-2547 ◽  
Author(s):  
Ritu Mamgain
Keyword(s):  
Click Chemistry ◽  
Good Yield ◽  
Cycloaddition Reaction ◽  
Triazole Derivatives ◽  
Biologically Relevant

A series of novel coumarin-1,2,3-triazole derivatives were synthesized in good yield via click chemistry using Cu(I) catalyzed intermolecular Huisgen [3+2] cycloaddition reaction. All the synthesized compounds were characterized spectroscopically. This piece of work could be helpful to develop biologically relevant coumarin analogs.

DABCO-Induced [2+2+2]-Cycloaddition Reaction of Ethyl Propiolate and Aryl Aldehydes for the Synthesis of 4-Aryl-4H-pyrans

Synlett ◽  
2009 ◽  
Vol 2009 (20) ◽  
pp. 3295-3298
Author(s):  
Huanfeng Jiang ◽  
Weibing Liu ◽  
Peng Zhou ◽  
Shifa Zhu
Keyword(s):  
Cycloaddition Reaction ◽  
Aryl Aldehydes

Diarylmethanols Synthesis by Nickel(II)-catalyzed Addition of Arylboronic Acids to Aryl Aldehydes

2020 ◽  
Vol 17 (4) ◽  
pp. 248-253 ◽  
Author(s):  
Fusheng Bie ◽  
Xuejing Liu ◽  
Meng Wang ◽  
Haizhu Cui ◽  
Tang Li ◽  
...  
Keyword(s):  
Good Yield ◽  
Aromatic Aldehydes ◽  
Imidazolium Chloride ◽  
Arylboronic Acids ◽  
Practical Procedure ◽  
Aryl Aldehydes ◽  
High Yields

A practical procedure for the addition of arylboronic acids to aromatic aldehydes has been developed in the presence of NiCl2(PPh3)2/1,3-bis-(2,6-diisopropylphenyl)imidazolium chloride (IPr·HCl) system with good yield. Generally, electron-rich and -neutral aryl aldehydes showed excellent reactivity and provided desired products in high yields. This procedure will provide new way to the synthesis of diarylmethanols.

The synthesis of 8-aza-3-deazaguanosine [6-amino-1-(β-D-ribofuranosyl)-υ-triazolo[4,5-c]pyridin-4-one] via a novel 1,3-dipolar cycloaddition reaction

1980 ◽  
Vol 58 (23) ◽  
pp. 2550-2561 ◽  
Author(s):  
Robert A. Earl ◽  
Leroy B. Townsend
Keyword(s):  
Spectral Data ◽  
Good Yield ◽  
Liquid Ammonia ◽  
Functional Group ◽  
Proton Nmr ◽  
Cycloaddition Reaction ◽  
Chemical Degradation ◽  
Dipolar Cycloaddition ◽  
Nuclear Overhauser Enhancement ◽  
Nuclear Overhauser

8-Aza-3-deazaguanosine (2) bas been prepared via a route which used a 1,3-dipolar cycloaddition reaction to provide a key intermediate. The reaction of 2′,3′,5′-tri-O-benzoyl-β-D-ribofuranosyl azide (13) with methyl 4-hydroxy-2-butynoate (11) provided a good yield of crystalline methyl 5-hydroxymethyl-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-υ-triazole-4-carboxylate (14). A series of functional group transformations were then used to convert 14 into methyl 5-cyanomethyl-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-υ-triazolo-4-carboxylate (19). Treatment of 19 with liquid ammonia effected not only a smooth removal of the blocking groups, but also an aminolysis of the ester function which was then followed by a ring annulation to provide 8-aza-3-deazaguanosine (2). The structures of these nucleosides were established on the basis of proton nmr spectral data and nuclear Overhauser enhancement data. The nucleosides obtained in this study were also converted through a chemical degradation sequence into nucleosides which had been obtained during an earlier work from our laboratory. The present study also provides unequivocal proof of the structures of some triazole nucleosides obtained in the earlier study.

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