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1. Chromans
&
Chromenes
Presented by:
Hadeel Fawzi Hammad &
Nesma Emad

2. Chromenes
Chromans
Chromenes also called benzopyrans, result
from the fusion of a benzene ring to a
heterocyclic pyran ring
4H-chromene 2H-chromene
Chromans (benzodihydropyran)
Chroman, or 3,4-dihydro-2H-1-benzopyran,
is itself not found in nature, but the
chroman unit is present in many natural
products.
Structure

3. Occurance
Chromenes
Chromans
Chromenes and its derivatives are an important
class of compounds and widely spread in nature.
A number of biologically-active chromenes have
been isolated from species of the genus
Piper.
Chromans present in many natural
products,such as Vitamin E (α-tocopherol),
a substituted chroman, is found in plant oils
and the leaves of green vegetables

4. Synthesis
Chromenes
Chromans
1) Condensation between aldehyde and
malanonitrile followed Michael addition with
resorcinol to afford 2-amino-4H-chromene
derivatives after rearomatization and
cyclization using water as a solvent.
1- Via the Heck coupling of allylic alcohols and 2-
iodophenols, followed by a reduction of the newly
formed ketone , followed by cyclization would then
afford the desired chroman ring
The utility and generality of this method is
demonstrated through the synthesis of a series of 2-
aryl-, 2-heteroaryl- and 2-alkylchromans, as well as an
azachroman derivative

5. Synthesis
Chromenes
Chromans
2) From Salicylaldehyde
2.1) Reaction of salicylaldehydes with ethyl 3-
methyl-2-butanoate led to the formation of
2,2-dimethyl-2H-chromenes. Reaction was
carried out in DMF at 130 °C.
2- convenient one-step synthesis of 2,2-
dimethylchromans from the nuclear
isoprenylation of phenols with isoprene. The
reaction with phloroglucinol gave 2,2
dimethylchroman-5,7-diol The reaction is
catalyzed by Amberlyst 15, a macroreticular
sulfonic acid cation exchange resin. in THF ,

6. Synthesis
Chromenes
Chromans
2.2) The condensation of salicylaldehydes
with olefins having two electron-withdrawing
groups were also reported for the synthesis of
chromenes. The reactions mainly gave polymerized
products, and the chromene products were
obtained in low yields.

7. (2) Rhodanines
Synthesis
Chromenes
Chromans
3) Reaction of arylidenemalononitriles with
dimedone (a) and 1,3-cyclohexanedione (b)
led to the formation of the tetrahydro- 4H-
chromene derivatives.

8. Occur
ance:
Reactions
Chromenes
Chromans
The ring-opening reaction of chromenes
In the absence of UV light, they exist in the closed,
uncolored form. Upon UV irradiation, the C2-O bond
breaks, and the open, colored form is produced.
Direct oxidation of chromans to chromenes can be
achieved using a hig potential quinone; chloranil and
dichlorodicyanobenzoquinone are suitable.

9. Applications:
• A rhodanine-based chemosensor RDV proved to be a practical sensor to
water sample analysis and cell imaging.
• Antiviral, anticancer, antimicrobial, and drug discovery.
• In drug discovery, rhodanines are special heterocyclic structure. Their derivatives
possess strong anti-bacterial activity and some of them have shown potent activity
against multidrug-resistant pathogens, both under in vitro and in vivo conditions. To
treat multi-drug resistant pathogens, the development of novel potent drugs, with
superior anti-bacterial efficacy, is most important. One of the promising paths is the
design and development of new rhodanine.
Occurance
:
Applications
Chromenes
Chromans
• It is known that number of naturally or
synthetically available compounds having
chromene as their important core structure
showing interesting pharmacological and
biological activities including anticancer,
antiviral, antimicrobial, anti-inflammatory
activities, antitumor, antioxidant, antifungal,
anti-influenza, anti HIV and anticoagulant.
• In addition, they can be used as for the treatment
of neurodegenerative diseases including
Alzheimer's disease.
Vitamin E is a fat-soluble vitamin with
several forms, but alpha-tocopherol is the
only one used by the human body also
boosting your immune system to help you fight
off viruses and pathogenic bacteria. Its main
role is to act as an antioxidant,

10. Applications:
• A rhodanine-based chemosensor RDV proved to be a practical sensor to
water sample analysis and cell imaging.
• Antiviral, anticancer, antimicrobial, and drug discovery.
• In drug discovery, rhodanines are special heterocyclic structure. Their derivatives
possess strong anti-bacterial activity and some of them have shown potent activity
against multidrug-resistant pathogens, both under in vitro and in vivo conditions. To
treat multi-drug resistant pathogens, the development of novel potent drugs, with
superior anti-bacterial efficacy, is most important. One of the promising paths is the
design and development of new rhodanine.
Occurance
:
Applications
Chromenes
Chromans
• Chromene derivatives play also an important role
in the production of highly effective fluorescent
dyes for daylight fluorescent pigments and
synthetic fibers.
• Chromenes with cyano-functionality has a wide
range of applications in chemistry such as lasers,
optical brighteners, fluorescence markers and
cosmetics.
. Anti-inflammatory, analgesic, antipyretic and other
pharmacological activities of a chroman derivative