Controlling factors determining the selective HSCN addition to double bonds and their application to the synthesis of 7-isothiocyano-7,8-alpha-dihydro-bisabolene

Abstract

A reatividade de duplas ligações terminal e trissubstituída de monoterpenos com HSCN foi examinada por CG evidenciando que fatores cinéticos são responsáveis pela adição quimiosseletiva em duplas ligações terminais em terpenos. O resultado mostra que a adição é cerca de 17 vezes mais rápida em duplas terminais do que em duplas trissubstituídas e que a presença do primeiro grupo SCN impede a entrada de um segundo grupo. A presença de um grupo hidroxila ou metoxila na molécula diminui sensivelmente a velocidade da reação. A partir do estudo acima foi possível elaborar e realizar a síntese do produto natural 7-isothiocyano-7,8-dihydro-a-bisabolene em duas etapas a partir do bisabolol.The reactivity of terminal and trisubstituted double bonds of monoterpenes with HSCN has been examined by GC giving evidence that kinetics is responsible for the chemoselective addition to terminal double bonds in terpenes. The results show that the addition to the terminal double bond is about 17 times faster than for trisubstituted double bonds and that the presence of the first SCN group in the molecule prevents a second addition. The presence of a hydroxyl or methoxy group in the molecule, decreases the reaction kinetics. Based on these kinetic experiments a two steps synthesis of the natural product 7-isothiocyano-7,8-dihydro-a-bisabolene using bisabolol as starting material, was planned and successfully accomplished.

Antitrypanosomal Activity of Novel Benzaldehyde-Thiosemicarbazone Derivatives from Kaurenoic Acid †

“…The synthetic route for the preparation of benzaldehyde-thiosemicarbazone derivatives of kaurenoic acid is presented in Scheme 1. The kaurenoic acid isothiocyanate and thiocyanate derivatives 2 and 3 were obtained as a mixture from a reaction between kaurenoic acid ( 1 ) and HSCN performed according to a previously reported procedure [34,35]. The reaction yield was of 58% of 2 and 33% of 3 .…”

“…Isothiocyanic acid [34,35]: a slurry of powdered KSCN (7.92 mmol) in CHCl 3 (20 mL) was triturated with KHSO 4 (7.92 mmol) in a mortar for 5 min. The HSCN chloroform solution was decanted, an additional 10 mL of CHCl 3 was added to the solid mixture, and the solution was again decanted.…”

Changes in primary metabolites and volatile organic compounds in cotton seedling leaves exposed to silver ions and silver nanoparticles revealed by metabolomic analysis

“…Hexanal was used as a quorum-sensing inhibitor to prevent diseases of Chinese cabbage and lettuce ( Zhang et al, 2018b ). 3-Cyclohexen-1-ol is a derivative of limonene, which is well known for its antimicrobial and antiseptic activities ( Oliveira et al, 2001 ; Magwa et al, 2006 ). It is noteworthy that these VOCs can be involved in the plant response to abiotic and biotic stresses, which suggests that the cotton leaves initially produce compounds to adapt to AgNP stress.…”

Antileishmanial and Antibacterial Activity of Essential Oils of Medicinal Plant Achillea santolina L.

“…Eucalyptol is one of the most important compounds as antibacterial activity (Leung and Foster, 2003). 3-Cyclohexen-1-ol, 4methyl-1-(1-methylethyl) which is derivative of limonene (Olivera et al, 2001) and Limonene has been implicated to be an effective antimicrobial agent (Magwa et al, 2006). Our results showed that Klebsiella pneumonia was the most sensitive bacteria to the plant oils from Deir Atiyah (21 mm), It is revealed that the Klebsiella pneumonia was sensitive to the essential oil of A. santolina from Iran with inhibition zone from 21.5 to 23 mm (Motavalizadehkakhky et al, 2013).…”