Studies toward the total synthesis of naturally occurring pyranonaphthoquinones from Ventilago harmandiana

Abstract

The enantioselective synthesis of a naturally occurring pyranonaphthoquinone isolated from a Thai endemic plant, Ventilago harmandiana, has been achieved. L-Rhamnose and gallic acid were used as the starting materials. A new C-1-glycosidation of L-rhamnal with trimethyl aluminum in the presence of a catalytic amount of ytterbium(III) triflate was developed. A new reagent, PhSCF2H/SnCl4, for the formylation of partially deactivated and hindered aromatic compounds has been introduced. Phenylthiophthalide was used efficiently as a cycloannulating agent in the Hauser cycloannulation reaction, employing slightly excess lithium t-butoxide as a base with a catalytic amount of lithium chloride. The synthetic route developed is applicable for the synthesis of other analogues with substituents at the aromatic and pyran rings.

UPLC-ESI-MRM/MS for Absolute Quantification and MS/MS Structural Elucidation of Six Specialized Pyranonaphthoquinone Metabolites From Ventilago harmandiana

“…Specialized metabolites, historically referred to as secondary metabolites, are chemical compounds that are not essential for supporting life of a given organism and are often extracted from medicinal plants for the study of their chemical structures and their biological activities ( Khoomrung et al, 2017 ). The plant Ventilago genus of the Rhamnaceae family contains more than 40 species and is found across India, South Asia ( Cooke and Johnson, 1963 ), and recently in Thailand ( Kongsriprapan et al, 2012 ). Various members of the Ventilago genus have been used as traditional medicines for numerous therapeutic treatments, e.g., diabetes, wounds, psoriasis, AIDS, diuretics, and arthritis ( Kongsriprapan et al, 2012 ; Molee et al, 2018 ), as well as anti-inflammation in both animal and cell line studies ( Wang et al, 2016 ; Panthong et al, 2020 ).…”

“…The plant Ventilago genus of the Rhamnaceae family contains more than 40 species and is found across India, South Asia ( Cooke and Johnson, 1963 ), and recently in Thailand ( Kongsriprapan et al, 2012 ). Various members of the Ventilago genus have been used as traditional medicines for numerous therapeutic treatments, e.g., diabetes, wounds, psoriasis, AIDS, diuretics, and arthritis ( Kongsriprapan et al, 2012 ; Molee et al, 2018 ), as well as anti-inflammation in both animal and cell line studies ( Wang et al, 2016 ; Panthong et al, 2020 ). Ventilago harmandiana Pierre ( V. harmandiana ) is an endemic plant that is found locally in the southern part of Thailand.…”

Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl) methane

“…In an initial attempt and on the basis of our previously reported work, 20 difluoro(phenylsulfanyl)methane (PhSCF 2 H, 1) 21 was allowed to react with 1,2,4-trimethoxybenzene (2a, 1 equiv) mediated by stannic chloride (SnCl 4 , 2 equiv based on 1) in dichloromethane at room temperature for 2 hours under an argon atmosphere. To our delight, three products, S,S′-diphenyl dithioacetal 3a (40% yield), aromatic aldehyde 4a (36% yield) and sulfide 5a (6% yield), were isolated (Table 1, entry 1).…”

Data_Sheet_1.docx

“…Specialized metabolites, historically referred to as secondary metabolites, are chemical compounds that are not essential for supporting life of a given organism and are often extracted from medicinal plants for the study of their chemical structures and their biological activities (Khoomrung et al, 2017). The plant Ventilago genus of the Rhamnaceae family contains more than 40 species and is found across India, South Asia (Cooke and Johnson, 1963), and recently in Thailand (Kongsriprapan et al, 2012). Various members of the Ventilago genus have been used as traditional medicines for numerous therapeutic treatments, e.g., diabetes, wounds, psoriasis, AIDS, diuretics, and arthritis (Kongsriprapan et al, 2012;Molee et al, 2018), as well as anti-inflammation in both animal and cell line studies (Wang et al, 2016;Panthong et al, 2020).…”

“…The plant Ventilago genus of the Rhamnaceae family contains more than 40 species and is found across India, South Asia (Cooke and Johnson, 1963), and recently in Thailand (Kongsriprapan et al, 2012). Various members of the Ventilago genus have been used as traditional medicines for numerous therapeutic treatments, e.g., diabetes, wounds, psoriasis, AIDS, diuretics, and arthritis (Kongsriprapan et al, 2012;Molee et al, 2018), as well as anti-inflammation in both animal and cell line studies (Wang et al, 2016;Panthong et al, 2020). Ventilago harmandiana Pierre (V. harmandiana) is an endemic plant that is found locally in the southern part of Thailand.…”