1.Geraniinic acid derivative from the leaves of Phyllanthus reticulatus.
Pojchaijongdee N1, Sotanaphun U, Limsirichaikul S, Poobrasert O. Pharm Biol. 2010 Jul;48(7):740-4. doi: 10.3109/13880200903273898.
Chemical constituents as well as cytotoxic and insecticidal activity of the crude methanol extract from the leaves of Phyllanthus reticulatus Poir. (Euphorbiaceae) were investigated. (5R*,6R*)-4,6-Dimethoxycarbonyl-5-[2',3',4'-trihydroxy-6'-(methoxycarbonyl) phenyl]-5,6-dihydro-2H-pyran-2-one (1) along with 3,4,3'-tri-O-methylellagic acid, and methyl gallate were isolated from the dichloromethane extract. Determination of their structures was based on spectroscopic analysis. Compound 1 possessed a very weak insecticidal activity against Spodoptera frugiperda (Sf9) with an IC(50) value of 27.27 microg/mL.
2.A 6-substituted-5,6-dihydro-2-pyrone from Cryptocarya strictifolia.
Juliawaty LD1, Kitajima M, Takayama H, Achmad SA, Aimi N. Phytochemistry. 2000 Aug;54(8):989-93.
The structure and absolute configuration of an alpha-pyrone isolated from Cryptocarya strictifolia was elucidated as 6R-(4'R,6'R-dihydroxy-8'-phenyloct-1'-enyl)-5,6-dihydro-2H-pyran-2 -one. Pinocembrin and lysicamine were also isolated.
3.Antiprotozoal 6-substituted-5,6-dihydro-alpha-pyrones from Raimondia cf. monoica.
Carmona D1, Sáez J, Granados H, Pérez E, Blair S, Angulo A, Figadere B. Nat Prod Res. 2003 Aug;17(4):275-80.
Dichloromethane extracts of both the roots and the leaves of Raimondia cf. monoica showed in vitro antiplasmodial and leishmanicidal activities against Plasmodium falciparum and Leishmania panamensis, respectively. Three 6-substituted 5,6-dihydro-2H-pyran-2-ones were isolated. (1) and (2) were identified as (6S)-(5'-oxohepten-1'E,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (1) and (6R)-(5'-oxohepten-1'Z,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (2), respectively. (-)-Arentilactone (3) was also isolated. The structure of the new compound (1) was determined by spectroscopic methods; additional spectroscopic data for (2) are reported for the first time.
4.Total synthesis and determination of the absolute configuration of 5,6-dihydro-α-pyrone natural product synargentolide B.
Prasad KR1, Gutala P. J Org Chem. 2013 Apr 5;78(7):3313-22. doi: 10.1021/jo400083v. Epub 2013 Mar 27.
Enantiospecific total synthesis and determination of the absolute stereochemistry of the α-pyrone-containing natural product synargentolide B were accomplished. The absolute stereochemistry of the natural product was established by synthesizing the possible diastereomers and comparison of the data with those reported for the natural product. During the process, total synthesis of the putative structure of related natural product 6R-[1S,2R,5R,6S-(tetraacetyloxy)-3E-heptenyl]-5,6-dihydro-2H-pyran-2-one was also accomplished and confirmed by X-ray crystal structure analysis. Wittig-Horner reaction of a chiral phosphonate derived from (S)-lactic acid and ring-closing metathesis were the key reactions during the course of the total synthesis.