Synthesis of the seed germination stimulant 3-methyl-2H-furo[2,3-c]pyran-2-one GavinR.Flematti, a, * EmilioL.Ghisalberti, a KingsleyW.Dixon b,c andRobertD.Trengove d a School of Biomedical and Chemical Sciences, The University of Western Australia, Crawley, WA 6009, Australia b Kings Park and Botanic Garden, West Perth WA 6005, Australia c School of Plant Biology, The University of Western Australia, Crawley WA 6009, Australia d School of Engineering Science, Murdoch University, Rockingham WA 6168, Australia Received9May2005;revised8June2005;accepted15June2005 Availableonline1July2005 Abstract—3-Methyl-2H-furo[2,3-c]pyran-2-one 1 wasrecentlyidentifiedasthekeyagentinsmoke,responsibleforpromotingthe seedgerminationofadiverserangeoffire-dependentandfire-independentplantspeciesfromaroundtheworld.Thesynthesisof thisnovelcompound,obtainedinthreestepsfrompyromeconicacid,isdescribed. Ó 2005 Elsevier Ltd. All rights reserved. 1. Introduction Recently,wehavereportedtheisolationofacompound from plant-derived smoke that is responsible for pro- moting the seed germination of a wide range of plant speciesfromAustralia,NorthAmericaandSouthAfri- ca. 1 The compound was identified as 3-methyl-2H- furo[2,3-c]pyran-2-one 1 on the basis of spectroscopic analysis (MS, 1 H NMR, 13 C NMR and 2D NMR). We now report the synthesis of this new bioactive compound. 2. Results and discussion Retrosynthetic analysis of 1 (Scheme 1) indicated that pyromeconic acid 2 would provide a useful starting compound. 2 Weenvisagedthattreatmentofthepropio- nylesterofpyromeconicacid 3 withastrongbase,such aslithiumdiisopropylamide(LDA),couldleadtocycli- sation and formation of the butenolide entity. This provedunsuccessful,soalternativemethodsforforming thebutenolidewereinvestigated. Other methods attempted included treatment of the propionylester 3 withaceticanhydrideasdescribedby Belskyetal. 3 Additionally, the analogous 2-chloropro- pionyl ester of pyromeconic acid was treated with tri- ethylphosphiteinanattempttoformthephosphonate, which could be treated under Horner–Emmons condi- tionstoformthebutenolide. 4,5 However,thesemethods failedtoyieldthedesiredproduct. Amorepromisingapproachwasthemethoddescribed by Ohkata et al. 6 for forming vinylogous 4H-pyrones from 4H-pyran-4-thione and arenyl bromomethyl ke- tones.Thus,the2-chloropropionylesterofpyromeconic acid 4 was converted to the corresponding thione 5 by 0040-4039/$-seefrontmatter Ó 2005ElsevierLtd.Allrightsreserved. doi:10.1016/j.tetlet.2005.06.077 Keywords: Butenolide; Germination stimulant; Seed germination; Smoke. * Corresponding author. Tel.: +61 8 6488 4465; fax: +61 8 6488 1005;e-mail: gflematt@chem.uwa.edu.au Scheme 1. Retrosynthetic approach to 3-methyl-2H-furo[2,3-c]pyran- 2-one 1. TetrahedronLetters46(2005)5719–5721 Tetrahedron Letters