Resumo

JORDAAN, Johan H. L.; SMIT, Frans J.; VOSLOO, Hermanus C. M.  e  VILJOEN, Agatha M.. Synthetic Possibilities for Hemilabile Ligands: A Case Study of Decacyclo[10.8.15,8.02,11.04,9.013,20.015,18]-heneicosane-3,10,14,19-tetraone. S.Afr.j.chem. (Online) [online]. 2023, vol.77, pp.163-170. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2023/v77a21.

As proof of the synthetic possibilities for hemilabile ligands the chemistry of decacyclo[10.8.1^5,8.0^2,11.0^4,9.0^13,20.0^15,18]heneicosane-3,10,14,19-tetraone (5) was investigated. Reacting 5 with ethylene glycol under acid conditions gave the expected di-acetal protected ketone (6) as four possible isomers. Reduction of these isomers to produce the dialcohol ketal (7) was only possible with LiAlH₄, after NaBH₄, Luche's, and Meerwein-Ponndorf-Verley reduction methods were unsuccessful. Deprotection of 7 to the hydroxyl ketone (8) derivative was not possible under reflux with a 25% HCl solution. To evaluate the reactivity of 5, and investigate alternative synthetic routes to Grubbs pre-catalysis, 5 was treated with the reducing agents i) NaBH₄, ii) glacial AcOH, Zn and iii) 80% AcOH/H₂O/Zn mixture, which resulted in various reduction products. The AcOH/H₂O/Zn reduction resulted in various products and a further investigation into the mechanism is given within this report.

Palavras-chave : Pentacycloundecane; Grubbs pre-catalyst; Cyclo-addition; Hemilabile ligands.

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