- Ruthenium-Catalyzed Oxidations of Alcohols
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A combination of low-valent ruthenium complexes and peroxides such as t-BuOOH and peracids serves as efficient catalytic systems for the oxidation of aromatic and aliphatic hydroxy compounds. The utility of these methods was demonstrated by the synthesis of acyl cyanides which are versatile synthetic intermediates. The principle of the catalytic oxidations with peracids lead to the novel and efficient method for aerobic oxidation of alcohols in the presence of aldehydes. This reaction is of importance in synthetic and large scale industrial processes and from environmental points of view. The present principle will provide new chemistry of oxidative transformations of various industrially important functional materials.
- Murahashi,Naota
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p. 203 - 213
(2007/10/03)
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- Ruthenium-catalyzed oxidations for selective syntheses of ketones and acyl cyanides. Selective acylation of amino compounds with acyl cyanides
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Oxidation of alcohols to the corresponding carbonyl compounds with tert-butyl hydroperoxide in the presence of dichlorotris(triphenylphosphine)ruthenium catalyst gives the corresponding carbonyl compounds with high efficiency. This method can be applied to the oxidation of cyanohydrins to give acyl cyanides which are versatile synthetic intermediates. Acylation of amino compounds with acyl cyanides thus obtained proceeds chemoselectively. Thus, the reaction of amino alcohols with acyl cynides gives N-acylated products exclusively. In the similar N-acylation of polyamines primary amines are selectively acylated in the presence of secondary amines. These reactions are highly useful for the synthesis of spermidine and spermine alkaloids such as spermidine alkaloids such as spermidine siderophores. Dimeric cyclocoupling reaction of diacyl cyanides such as iso- and terephthaloyl cyanides with polyamines can be performed under the similar reaction conditions to give the corresponding polyazamacrocycles with high efficiency.
- Murahashi,Naota
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p. 433 - 440
(2007/10/02)
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- N-METHOXYDIACETAMIDE: A NEW SELECTIVE ACETYLATING AGENT
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A simple and efficient method for the direct chemoselective acetylation of primary amines in the presence of alcohols or secondary amines using a new reagent N-methoxydiacetamide is described.
- Kikugawa, Yasuo,Mitsui, Kimiyo,Sakamoto, Takeshi,Kawase, Masami,Tamiya, Hiroshi
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p. 243 - 246
(2007/10/02)
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- Chemoselective Acylation of Primary Amines in the Presence of Secondary Amines with Acyl Cyanides. Highly Efficient Methods for the Synthesis of Spermidine and Spermine Alkaloid
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Acyl cyanides are highly useful reagents for the chemoselective acylation of primary amines in the presence of secondary amines.The reaction provides the versatile method for the shortstep synthesis of various naturally occurring polyamines.
- Murahashi, Shun-Ichi,Naota, Takeshi,Nakajima, Nobuyuki
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p. 879 - 882
(2007/10/02)
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- HIGH CHEMOSELECTIE SYNTHESIS OF CARBOXAMIDES BY USING SYN-PHENYLPYRIDYL-O-ACYL OXIMES(PPKO)
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Various carboxamides are prepared chemoselectively in good yields by using syn-phenylpyridyl ketoxime(PPKO) as functional leaving group.
- Miyasaka, Tadayo,Noguchi, Shunsaku
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p. 701 - 704
(2007/10/02)
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- Peptide Synthesis with Benzo- and Naphthosultones
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6-Nitro- and 6,8-dinitronaphth-1,2-oxathiole S,S-dioxides (7b and 7c) have been prepared from the parent naphthosultone 7a and compared with 5-nitrobenz-3H-1,2-oxathiole S,S-dioxide (1b) as coupling reagents for peptide synthesis.Nucleophilic attack of a carboxylate salt on these strained five-membered sultones leads to activated esters 3 and 9 which rapidly react with amines (except in the case of 9c).The rate constant for the formation of ester 9b is higher than that of 3b.Amides or peptides are formed in slightly better yields with the naphthosultone 7b than with the benzosultone 1b.The naphthosultones are also preferred over the benzosultones from the point of view of amount of 5(4H)-oxazolone formation from N-benzoyl amino acids and the degree of racemization.However the rate of alkaline hydrolysis of 7b is slower than that of 1b.All these results may be rationalized by a better intramolecular acyl transfer reaction in the more rigid mixed anhydride intermediate 8b.There is no dependence on in the rate equation for aminolysis of esters 3b and 9b by benzylamine in THF, acetonitrile, or DMF and the aminolysis is probably anchimerically assisted by a neighbouring S=O group.Esters 3b are more selective acylating agents for primary amino groups in the presence of secondary ones than esters 9b and this observation is exploited in a synthesis of maytenine by selective acylation of spermidine.
- Acher, Francine,Wakselman, Michel
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p. 4133 - 4138
(2007/10/02)
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- ONE-POT SELECTIVE ACYLATION OF AMINES USING 3,6-DIETHYL-2-HYDROXYPYRAZINE AS ACYL CARRIER
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Introduction of 3,6-diethyl-2-hydroxypyrazine into a system of amide syntheses using acyl diethylphosphates resulted in the performance of selective acylation in satisfactory yields.
- Ohta, Akihiro,Inagawa, Yukiko,Okuwaki, Yukari,Shimazaki, Makoto
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p. 2369 - 2373
(2007/10/02)
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- ACTIVATION OF CARBOXYL GROUPS BY DIPHENYL 2-OXO-3-OXAZOLINYLPHOSPHONATE. FACILE PREPARATION OF VERSATILE REAGENTS, 3-ACYL-2-OXAZOLONES
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Synthetic utility of the 2-oxazolone moiety as an excellent new leaving group is described.Based on such a function of the heterocycles, diphenyl 2-oxo-3-oxazolinylphosphonate has been newly introduced as a carboxyl-activating reagent which permits a facile direct preparation of 3-acyl-2-oxazolones and amides including peptides from a wide variety of carboxylic acids.The 3-acyl-2-oxazolides also serve as versatile reactive agents for highly chemoselective acyl-transfer to the nucleophilic species such as amines, alcohols and thiols, providing convenient and high-yield routes to amides, esters and thiol esters under mild conditions.They are also useful intermediates for ketones and alcohols.
- Kunieda, Takehisa,Higuchi, Tsunehiko,Abe, Yoshihiro,Hirobe, Masaaki
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p. 3253 - 3260
(2007/10/02)
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- Chemistry of Naturally Occuring Polyamines. 1. Total Synthesis of Celacinnine, Celabenzine, and Maytenine
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New methods for the selective functionalization of spermidine and other naturally occurring polyamines have been employed in highly convergent total syntheses of the title compounds.
- McManis, James S.,Ganem, Bruce
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p. 2041 - 2042
(2007/10/02)
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- MONITORED AMINOLYSIS OF 3-ACYLTHIAZOLIDINE-2-THIONE : A NEW CONVENIENT SYNTHESIS OF AMIDE
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3-Acylthiazolidine-2-thiones (1) were easily prepared and they were treated with several amines in dichloromethane to give amides 4 in very high yields within a short time.Aminoalcohols and aminophenols were selectively converted into acylaminoalcohols and acylaminophenols, respectively, by this reaction.One can monitor the reaction by disappearance of the yellow color of the starting material 1.Some amide alkaloids (15-18) have effectively been synthesized.
- Nagao, Yoshimitsu,Seno, Kaoru,Kawabata, Kohji,Miyasaka, Tadayo,Takao, Sachiko,Fujita, Eiichi
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p. 841 - 844
(2007/10/02)
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