A concise route to branched erythrono-gamma-lactones. Synthesis of the leaf-closing substance potassium (+/-)-(2R,3R)-2,3,4-trihydroxy-2-methylbutanoate.
A series of 1,2-dioxanes 3 were ring-opened with Co(SALEN)(2) to furnish lactol regioisomers 4 and 5 (86-99% yield). The lactols were oxidized to gamma-lactones 8 and 9 (72-96% yield) and deprotected to afford the 2-C- and 3-C-alkyl and aryl branched erythrono-gamma-lactones 1, 6, and 7 (65-94% yield), including the natural plant lactone (+/-)-2-C-d-methylerythrono-1,4-lactone 1. The latter compound was treated with aqueous potassium hydroxide to afford potassium (+/-)-(2R,3R)-2,3,4-trihydroxy-2-methylbutanoate 2, which is a leaf-closing substance of Leucaena leucocephalam.
Pedersen
Daniel Sejer
DS
Department of Chemistry, The University of Adelaide, South Australia 5005, Australia.
Robinson
Tony V
TV
Taylor
Dennis K
DK
Tiekink
Edward R T
ER
D001688:Biological Products / Q000138:chemical synthesis; D004146:Dioxanes / Q000737:chemistry; D007783:Lactones / Q000138:chemical synthesis*; D018515:Plant Leaves / Q000737:chemistry; D010944:Plants / Q000737:chemistry*; D013400:Sugar Acids / Q000138:chemical synthesis*
C465974:2,3,4-trihydroxy-2-methylbutanoic acid; D001688:Biological Products; D004146:Dioxanes; D007783:Lactones; D013400:Sugar Acids