1-Nicotinoylbenzotriazole: A Convenient Tool for Site-Selective Protection of 5,7-Dihydroxycoumarins

1-Nicotinoylbenzotriazole (NicBt) was uncovered as an efficient protecting agent for the site-selective acylation of resorcinol-type phenolic groups with almost equal reactivity. The use of NicBt allows selective protection of the 7-OH group in 5,7-dihydroxycoumarins in one simple scalable step, whi...

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Published inSynthesis (Stuttgart) Vol. 51; no. 19; pp. 3617 - 3624
Main Authors Fatykhov, Ramil F., Khalymbadzha, Igor A., Chupakhin, Oleg N., Charushin, Valery N., Inyutina, Anna K., Slepukhin, Pavel A., Kartsev, Victor G.
Format Journal Article
LanguageEnglish
Published STUTTGART Thieme Medical Publishers 01.10.2019
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
STRAINS
phenols
natural products
protecting groups
CALANOLIDES
esterification
ANALOGS
BIOLOGICAL EVALUATION
total synthesis
acylation
ACYLBENZOTRIAZOLES
COUMARIN DERIVATIVES
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Summary:1-Nicotinoylbenzotriazole (NicBt) was uncovered as an efficient protecting agent for the site-selective acylation of resorcinol-type phenolic groups with almost equal reactivity. The use of NicBt allows selective protection of the 7-OH group in 5,7-dihydroxycoumarins in one simple scalable step, while combination of the nicotinoylation with tosylation-denicotinoylation or silylation-denicotinoylation yields 5-OH-protected 5,7-dihydroxycoumarins. Furthermore, nicotinoylated 5,7-dihydroxycoumarins proved useful in a gram-scale three-step preparation of a 2,2-dimethylpyrano[2,3- f ]coumarin, a key intermediate for the synthesis of calanolide A, an HIV reverse transcriptase and Mycobacterium tuberculosis inhibitor, and its active analogues.
ISSN:0039-7881
1437-210X
DOI:10.1055/s-0039-1690104