Exceptionally facile reduction of acyclic and alicyclic carboxylic acids to aldehydes by thexylchloroborane-dimethyl sulfide

Brown, Herbert C.; Soon, Jin; Nazer, Behrooz; Yoon, Nung Min

doi:10.1021/ja00337a075

Cited by 53 publications

(12 citation statements)

References 2 publications

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“…The most difficult step in the synthesis was the formation of aldehyde 4. Several methods for aldehyde synthesis (8,20,23,29,35) were unsuccessful; the chromium-and aluminum-containing reagents used for this purpose may have been inappropriate due to the chelating abilities of the synthetic intermediates. Furthermore, the heterocyclic and phenolic groups of carboxylic acid 3 and alcohol 5 may have interfered with the action of reagents used to generate the aldehyde intermediate.…”

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confidence: 99%

Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa

et al. 1988

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Pyochelin, a phenolic siderophore of Pseudomonas aeruginosa, was synthesized in three steps from salicylonitrile, L-cysteine, and L-N-methylcysteine. The synthetic product was determined to be identical to natural pyochelin by 1H nuclear magnetic resonance spectroscopy, fast atom bombardment mass spectrometry, chromatographic analysis, and chemical reactivity with FeCl3 and ammoniacal silver nitrate reagent. Synthetic and natural pyochelin promoted bacterial growth in iron-depleted medium and were also found to mediate iron transport by P. aeruginosa to the same levels. Neopyochelin, a stereoisomeric by-product of the synthesis, showed less biological activity than did pyochelin in iron transport assays.

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confidence: 99%

Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa

et al. 1988

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“…Soon after, the reagent is found to be an excellent reducing agent for the direct conversion of carboxylic acids to the corresponding aldehydes. 11,12 The slow addition of 10% excess reagent (2.2 equiv) to one equivalent of compound in methylene chloride at 0 o C for the hydrogen evolution stage, followed by reduction at room temperature, is optimum for the reduction to aldehyde. Generally, the yields of aromatic series are lower than those in the aliphatic series.…”

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confidence: 99%

“…(10) (11) Similarly, the general reducing characteristics of thexylbromoborane-methyl sulfide (ThxBHBr·SMe 2 )…”

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Thirty Six Years of Research on the Selective Reduction and Hydroboration

Soon¹

2011

Bulletin of the Korean Chemical Society

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thirty six years, the author and his collaborators have developed a variety of reducing and hydroborating agents, and applied them to organic synthesis, which involves the 1,2-reduction of α,β-unsaturated carbonyl compounds, stereoselective reduction of cycloalkanones, regioselective ring-opening of epoxides, partial reduction of carboxylic acid derivatives to aldehydes, regioselective addition to carbon-carbon multiple bonds, etc. by utilizing metal hydrides and the newly-devised the Meerwein-Ponndorf-Verley (MPV) type reagents. Such developments provide a new synthetic methodology making possible valuable selective reductions and hydroborations, not practical previously.

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“…[1][2][3]5 Among them, thexylhaloboranes, 5,6 the 9-BBN system with metal hydrides 7 and the reduction-oxidation procedure 8 seem to afford the most satisfactory results. However, every reducing system possesses its own limitation in use.…”

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“…However, every reducing system possesses its own limitation in use. For examples, the yields of aromatic aldehydes by thexylhaloboranes 5,6 are relatively low and variable upon the substituents on benzene ring; the 9-BBN system with metal hydrides 7 and the reductionoxidation procedure 8 can not be compatible with readily reducible functions other than carboxylic acid group. Therefore, chemists should find which procedure is suitable for their compounds to be transformed.…”

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Conversion of Carboxylic Acids to Aldehydes with Cyclic Dialkyldiaminoaluminum Hydrides.

Soon

Moon

2003

ChemInform

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A series of bis(dialkylamino)aluminum hydride reagents, which possesses various dialkylamines of different steric environments, has been reported as good reducing agents for the direct conversion of free carboxylic acids to the corresponding aldehydes. [1][2][3] In continuation of our efforts to explore new reducing agents for such transformation, we prepared cyclic dialkyldiaminoaluminum hydrides (1 and 2) and examined their general reducing action toward various organic functional groups. In the course of a systematic study, we found that these cyclic diaminoaluminum hydrides appear to be the reagents of choice for converting aromatic carboxylic acids to the corresponding aldehydes. Herein, we report such a transformation using newly-devised reducing agents. Results and DiscussionThe reagents 1 and 2 are readily prepared by a simple reaction of aluminum hydride (AlH 3 ) with N,N'-dialkylethylenediamine (1, R = Me; 2, R = Et) in THF (Eq. 1). A solution of aluminum hydride in THF reacts with diamines readily to evolve 2 equiv of hydrogen. : an extended period of reaction time at room temperature was needed to reduce even aldehydes and ketones. However, rather surprisingly, the reduction of aromatic carboxylic acids proceeded relatively faster after the evolution of 1 equiv hydrogen and stopped at the aldehyde stage. This phenomenon indicates that the acyloxyalane intermediate 3 is favorable to the reduction by the reagent but the resultant aldehyde intermediate 4 is relatively stable toward the further reduction (Eq. 2). However, the reaction of aliphatic carboxylic acids provided unsatisfactory results : over reduction to the alcohol stage is favorable under these reaction conditions.We performed all the reductions under the standardized reaction conditions at 25 o C: we have not tried to get a maximum yield in each reaction of carboxylic acids. The general trend of aldehyde synthesis from carboxylic acids with these reagents has been examined and the results are summarized in Table 1.Both the reagents reduce aromatic carboxylic acids to(1) † This paper is dedicated to Professor Sang Chul Shim for his distinguished achievements in chemistry.(2)

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Exceptionally facile reduction of acyclic and alicyclic carboxylic acids to aldehydes by thexylchloroborane-dimethyl sulfide

Cited by 53 publications

References 2 publications

Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa

Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa

Thirty Six Years of Research on the Selective Reduction and Hydroboration

Conversion of Carboxylic Acids to Aldehydes with Cyclic Dialkyldiaminoaluminum Hydrides.

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