A Facile Alkylation of Aryl Aldehyde Tosylhydrazones with Trialkylboranes

Kabalka, George W.; Maddox, John T.; Bogas, Ekaterini

doi:10.1021/jo00098a008

Cited by 23 publications

(2 citation statements)

References 15 publications

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“…The low yield in the reaction of 1b with hexenyl- B -9-BBN (entry 7) was due to competitive protodeborination during oxidation . It has been reported that benzylic boranes with further anion stabilizing groups attached are especially prone to such a process . In contrast, quenching the borane with benzaldehyde gave the corresponding homoallylic alcohol 2j in 96% yield with very high anti selectivity and high Z selectivity (Scheme ).…”

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confidence: 99%

Asymmetric Sulfur Ylide Reactions with Boranes: Scope and Limitations, Mechanism and Understanding

et al. 2007

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The reactions of aryl-stabilized sulfur ylides with organoboranes has been studied under a variety of conditions. At 5 or -78 degrees C, the reaction with Et3B gave a mixture of the first and second homologation products, but at -100 degrees C, only the first homologation product was obtained even with just 1.1 equiv of Et3B. Under these optimized conditions, the chiral sulfur ylides (derived from camphor sulfonic acid) with different aryl groups were reacted with Et3B to give the corresponding alcohols (95-98% yield, 96-98% ee) and amines (74-77% yield, >98% ee). The origin of the high enantioselectivity is discussed. The use of nonsymmetrical 9-BBN derivatives was also explored. It was found that whereas primary alkyl substituents gave mixtures of products derived from competing migration of the boron substituent and the boracycle, all other groups resulted in either exclusive migration of the boron substituent (Ph, hexenyl, i-Pr) or exclusive migration of the boracycle (hexynyl, cyclopropyl). The factors responsible for the outcome of the reactions involving a hindered (i-Pr) and an unhindered (propynyl) substituent were studied by DFT calculations. This revealed that, in the case of an unhindered substituent, the conformation of the ate complex is the dominant factor whereas, in the case of a hindered substituent, the barriers to interconversion between the conformers of the ate complex and subsequent migration control the outcome of the reaction.

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Section: Resultsmentioning

confidence: 99%

Asymmetric Sulfur Ylide Reactions with Boranes: Scope and Limitations, Mechanism and Understanding

et al. 2007

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“…JOURNAL OF CHEMICAL RESEARCH 2018 41 facile metal-free alkylation of aryl aldehyde tosylhydrazones with trialkylboranes. 25,26 In 2009, Barluenga et al developed a metal-free coupling reaction between N-tosylhydrazones and boronic acids. 27 Subsequently, coupling reactions of various sulfonylhydrazones with arylboronic acids were studied and applied in organic synthesis.…”

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confidence: 99%

Synthesis of 3-Aryl-1-Indanones via CsF-Promoted Coupling of Arylboronic Acids with N-Tosylhydrazones

Liu

Chen

Liu

et al. 2018

Journal of Chemical Research

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Thus, the synthesis of 3-aryl-1-indanone and its derivatives by efficient methods has attracted considerable attention. [3][4][5] The construction of the 3-aryl-1-indanone skeleton generally uses one or other of the following methods: (a) tandem Friedel-Crafts acylation and Nazarov cyclisation of arenes with α,β-unsaturated acyl chlorides in the presence of AlCl 3 (Scheme 1a); 6-8 (b) rhodium-catalysed hydroacylation of 2-vinyl benzaldehyde systems (Scheme 1b); 9,10 (c) zeolitecatalysed cyclisation of arylvinylketones (Scheme 1c); 11,12 (d) superacid-catalysed reactions of arenes and cinnamic acid (Scheme 1d); 13-15 (e) gold-catalysed oxidative cyclisations of cis-3-en-1-ynes to form cyclopentenone derivatives (Scheme 1e). [16][17][18] Tosylhydrazones, which are diazo precursors, are useful synthetic intermediates that have featured in several recent reports.A series of 17 3-aryl-1-indanones, four of which are novel, were prepared in good yield via a CsF-promoted reductive cross-coupling of the monotosylhydrazone of a 1,3-indanedione with an arylboronic acid. The method demonstrates wide substrate scope and good functional group tolerance. Moreover, the 3-aryl-1-indanones could also be prepared on a multi-gram scale.

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