2-(4-Methyl-pentene-3-one-2-yl)-1,3-dioxolane 5-(1,3-Dioxolan-2-yl)-2-methylpent-2-en-4-one 56055-61-9 Pent-2-en-4-one, 5-(1,3-dioxolan-2-yl)-2-methyl-