How to Remember Chromone Formulas

     Rule eleven –
     do not be haughty
         make way.

  Chromones are derivatives of 9,10–benzogamma–pyrone. The Latin letter “gamma” indicates that the carbonyl group is located opposite the heteroatom of oxygen (in the para position).

  9,10–Benzogamma–pyrone (= Chromone)

  Among simple chromones, 3-methylchromone can be noted, constructed according to its name.

  3-Methylchromone

  In furanochromones, the furanose ring is attached linearly. It is unsaturated, like in furanocoumarins, meaning it has one double bond. This is the most common subgroup of chromones, from which you need to know kellin and visnagin.

Kellin                                                     Visnagin
 
  Kellin has two methoxy groups –OCH₃, located opposite each other in the benzene ring (positions C₅ and C₈), and one methyl group at position C₂ of the pyranose ring.
  If one methoxy group (at C₈) is removed from kellin, we obtain visnagin. The name “visnagin” is very easy to confuse with visnadin, which, as we have already mentioned, belongs to coumarins. Remember that one of the most well-known sources of chromones (and specifically chromones!) is Visnaga daucoides Gaertn. (family Apiaceae), which contains visnagin. The coumarin visnadin is also found in Visnaga daucoides, but it is not the main compound. Knowing this will help you somewhat simplify the assimilation of chromones (draw an analogy: visnaga – visnagin).
 
  Regarding pyranochromones, you just need to know their structure. Obviously, you have already understood that they must have a pyranose ring. The pyranose ring is attached angularly, and it is unsaturated (has a double bond). Very often, two methyl groups are attached to the carbon atom adjacent to the heteroatom of oxygen in this pyranose ring (which is also characteristic of pyranocoumarins).
  Among individual pyranochromones, remember sorbifol, found in the leaves of rowan Sorbus aucuparia L., as is clear from the name (sorbus folium). We provide its formula as an example; it is not mandatory to memorize for our department (unlike all other formulas discussed earlier).

  Sorbifol

  Benzochromones contain a benzene ring attached angularly. One of the benzochromones is eleutherinol (source – the plant Eleutherococcus senticosus, family Iridaceae) – it contains two –CH₃ groups (at positions C₂ and C₅ of the chromone skeleton) and two –OH groups, located in the meta position in the benzene ring.

  Eleutherinol