Mint lactone

Group 11 is the home for mint lactone (Flavis 10.036, FEMA 3764) and various phthalides, which are well known from the flavour chemistry of celery. 

Lactones occur as natural odorants in aU major food commodities, including meat and meat products, milk, dairy products, cereals, fruits, vegetables and various beverages, such as tea, wine and spirits. Odour-active compounds in foods are y-and 5-lactones derived from aliphatic saturated and unsaturated y-hydroxycarboxyHc and 5-hydroxycarboxylic acids derived from fatty acids or sugars, but some lactones also arise from other precursors (e.g. mint lactone is a terpenoid compound and pantolactone is produced by hydrolysis of pantothenic acid via pantoic acid). Some lactones derived from aromatic hydroxycarboxyhc acids are also common compounds. The most important representatives of these compounds are phthahdes that are 3fL-isobenzofuran-l-ones (8-98) and coumarins (8-99) that are 2fL-l-benzopyran-2-ones (5-lactones of 2-hydroxycinnamic acids). 

An example of terpenoid lactones that widely occur in plants is monoterpenic lactone (6R,7aR)-3,6-dimethyl-5,6,7,7a-tetrahydro-4H-l-benzofuran-2-one, known as mint lactone (8-115), with mint, herbaceous and coumarinic odours that is found together with related lactones in the essential oil of peppermint Mentha x piperita, Lamiaceae), pennyroyal (M. pulegium) and other mint oils. 

Reaction of ketones and a,a-dimethoxyketones in the presence of TiCl4-Bu3N led to the formation of a,p-unsaturated lactones, which were converted to 2,3,4-trisubstituted furans. One of the examples is the preparation of menthofuran, the natural mint perfume <02CC2542>. 

Synthesis of mintlactone and isomintlactone, terpene lactones from mint oil 02S2155. 

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