Download - MEDICINAL CHEMISTRY- HETEROCYCLIC COMPOUNDS
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Heterocyclic compound:
A heterocyclic compound is a cyclic
compound which has atoms of at least two
different elements as members of its
ring(s).[1] The counterparts of heterocyclic
compounds are homocyclic compounds,
the rings of which are made of a single
element.
http://en.wikipedia.org/wiki/Cyclic_compoundhttp://en.wikipedia.org/wiki/Cyclic_compoundhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Homocyclic_compoundhttp://en.wikipedia.org/wiki/Homocyclic_compoundhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Cyclic_compoundhttp://en.wikipedia.org/wiki/Cyclic_compound -
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, a heterocyclic compoundPyridine
http://en.wikipedia.org/wiki/Pyridinehttp://en.wikipedia.org/wiki/Pyridinehttp://en.wikipedia.org/wiki/File:Pyridine.svg -
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cyclo-octasulfur, a homocyclic compound
http://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/File:Cyclooctasulfur_structural_formula_3D.svghttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfurhttp://en.wikipedia.org/wiki/Allotropes_of_sulfur -
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Although heterocyclic compounds may beinorganic, most contain at least one carbonatom, and one or more atoms of elements
other than carbon within the ring structure,such as sulfur, oxygen ornitrogen.[2] Since inorganic chemistry non-carbons usually areconsidered to replace carbon atoms, they are
called heteroatoms, meaning 'different fromcarbon and hydrogen' (rings of heteroatomsof the same element are homocyclic).
http://en.wikipedia.org/wiki/Compoundhttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/Heteroatomhttp://en.wikipedia.org/wiki/Heteroatomhttp://en.wikipedia.org/wiki/Organic_chemistryhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Heterocyclic_compoundhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Inorganic_compoundhttp://en.wikipedia.org/wiki/Compound -
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Heterocyclic chemistry is the branch of
chemistry dealing with synthesis,
properties, and applications of
heterocycles.
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Heterocyclic compounds in
selected areas of life:
in general: nucleic acids, amino acids(proteins), Chlorophyll
feeding: proteins, carbohydrates, vitamins
alkaloids: nicotine, caffeine
antibiotics (penicillins, sulfonamides)
psychopharmacologic agents
(benzodiazepines) insecticides (triazoles)
herbicides (triazines, pyridines)
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Properties:
cyclic systems with carbon and hetero-atoms
(N, O, S)
heteroaliphatic compounds:
similar properties like aliphatic compounds
heteroaromatic compounds: similar properties like aromatic compounds
Size of the cyclic system:
5-7 atoms: stable, easy to synthesise
> 7 atoms: stable, hardly to synthesise < 5 atoms: unstable, more or less easy
to synthesise
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HeterocyclesAcceptable prefixes include:
O=Oxa
S=Thia
N=Aza
When there is more than one hetero-atom,
preference is given to O, then S, then N, thenC. Mnemonic: Old Soldiers Never Cry.
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Suffix:
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Suffixes for fully
saturated compounds
Suffixes for fully
unsaturated compound
Ring size
Without N
With N
Without NWith N
-iraneiridine-ireneIrine3
-etaneetidine-ete-ete4
-olaneolidine-ole-ole5
-inane-in-ine6
-epane-epin-epine7
-ocaneocin-ocine8
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Oxygen Containing Heterocycles
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Heterocycles Containing
Nitrogen
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Five-membered Rings Containing
Nitrogen and Another Heteroatom
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Heterocycles Containing Sulfur
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6 Membered Rings Containing One
Nitrogen
Piperidine Pyridine
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6 Membered Rings Containing Two
Nitrogens
Piperazine
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7 Membered Rings
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More Complex Unsaturated Ring
Systems
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More Complex Unsaturated Ring
Systems
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Examples in Drugs
Naphazoline Captopril
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Diazepam Cyprohepatidine
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Nizatidine Phenytoin
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Ciprofloxacine
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Classification based on
electronic structure: Heterocyclic compounds can be usefully
classified based on their electronic
structure. The saturated heterocycles
behave like the acyclic derivatives. Thus,piperidine and tetrahydrofuran are
conventional amines and ethers, with
modified steric profiles. The study ofheterocyclic chemistry therefore focuses
especially on unsaturated derivatives.
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, and the preponderance of work and
applications involves unstrained 5- and 6-
membered rings. Included are pyridine,
thiophene, pyrrole, and furan. Anotherlarge class of heterocycles are fused to
benzene rings, which for pyridine,
thiophene, pyrrole, and furan arequinoline, benzothiophene, indole, and
benzofuran, respectively.
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Fusion of two benzene rings gives rise to a
third large family of compounds,
respectively the acridine,
dibenzothiophene, carbazole, anddibenzofuran. The unsaturated rings can
be classified according to the participation
of the heteroatom in the pi-system
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3-Membered rings:
Heterocycles with three atoms in the ring
are more reactive because of ring strain.
Those containing one heteroatom are, in
general, stable. Those with twoheteroatoms are more likely to occur as
reactive intermediates.
Common 3-membered heterocycles withone heteroatom are:
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UnsaturatedSaturatedHeteroatom
AzirineAziridineNitrogen
OxireneOxirane (ethylene oxide,
epoxides)
Oxygen
ThiireneThiirane (episulfides)Sulfur
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Those with two heteroatoms include:
UnsaturatedSaturatedHeteroatom
DiazirineNitrogen
OxaziridineNitrogen/oxygen
DioxiraneOxygen
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4-Membered rings:
Compounds with one heteroatom:
UnsaturatedSaturatedHeteroatom
AzeteAzetidineNitrogen
OxeteOxetaneOxygen
ThieteThietaneSulfur
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Compounds with two heteroatoms:
HeteroatomSaturatedUnsaturated
NitrogenDiazetidine
OxygenDioxetaneDioxete
SulfurDithietaneDithiete
http://en.wikipedia.org/w/index.php?title=Diazetidine&action=edit&redlink=1http://en.wikipedia.org/wiki/Dioxetanehttp://en.wikipedia.org/w/index.php?title=Dioxete&action=edit&redlink=1http://en.wikipedia.org/wiki/Dithietanehttp://en.wikipedia.org/wiki/Dithietehttp://en.wikipedia.org/wiki/Dithietehttp://en.wikipedia.org/wiki/Dithietanehttp://en.wikipedia.org/w/index.php?title=Dioxete&action=edit&redlink=1http://en.wikipedia.org/wiki/Dioxetanehttp://en.wikipedia.org/w/index.php?title=Diazetidine&action=edit&redlink=1 -
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5-Membered rings:
With heterocycles containing five atoms,
the unsaturated compounds are frequently
more stable because ofaromaticity.
Five-membered rings with one
heteroatom:
http://en.wikipedia.org/wiki/Unsaturated_compoundhttp://en.wikipedia.org/wiki/Aromaticityhttp://en.wikipedia.org/wiki/Aromaticityhttp://en.wikipedia.org/wiki/Unsaturated_compound -
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HeteroatomSaturatedUnsaturated
Nitrogen(Azolidine isPyrrolidine
not used)
(Azole is notPyrrole
used)
Oxygen(OxolaneTetrahydrofuran
is rare)
(Oxole is notFuran
used)
SulfurThiolane(Thiole is notThiophene
used)
BoronBorolaneBorole
PhosphorusPhospholanePhosphole
ArsenicArsolaneArsoleAntimonyStibolaneStibole
BismuthBismolaneBismole
SiliconSilolaneSilole
TinStannolaneStannole
http://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Pyrrolidinehttp://en.wikipedia.org/wiki/Pyrrolehttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Tetrahydrofuranhttp://en.wikipedia.org/wiki/Furanhttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Thiolanehttp://en.wikipedia.org/wiki/Thiophenehttp://en.wikipedia.org/wiki/Boronhttp://en.wikipedia.org/wiki/Borolehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Phospholehttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Arsolehttp://en.wikipedia.org/wiki/Antimonyhttp://en.wikipedia.org/wiki/Stibolehttp://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Bismolehttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Silolehttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Stannolehttp://en.wikipedia.org/wiki/Stannolehttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Silolehttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Bismolehttp://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Stibolehttp://en.wikipedia.org/wiki/Antimonyhttp://en.wikipedia.org/wiki/Arsolehttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Phospholehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Borolehttp://en.wikipedia.org/wiki/Boronhttp://en.wikipedia.org/wiki/Thiophenehttp://en.wikipedia.org/wiki/Thiolanehttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Furanhttp://en.wikipedia.org/wiki/Tetrahydrofuranhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Pyrrolehttp://en.wikipedia.org/wiki/Pyrrolidinehttp://en.wikipedia.org/wiki/Nitrogen -
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The 5-membered ring compounds
containing two heteroatoms, at least one
of which is nitrogen, are collectively called
the azoles. Thiazoles and isothiazolescontain a sulfur and a nitrogen atom in the
ring. Dithiolanes have two sulfur atoms.
http://en.wikipedia.org/wiki/Azolehttp://en.wikipedia.org/wiki/Thiazolehttp://en.wikipedia.org/wiki/Isothiazolehttp://en.wikipedia.org/wiki/Dithiolanehttp://en.wikipedia.org/wiki/Dithiolanehttp://en.wikipedia.org/wiki/Isothiazolehttp://en.wikipedia.org/wiki/Thiazolehttp://en.wikipedia.org/wiki/Azole -
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HeteroatomSaturatedUnsaturated (and
partially unsaturated)
Nitrogen/nitrogenImidazolidine
Pyrazolidine
)Imidazoline(Imidazole
)Pyrazoline(Pyrazole
Nitrogen/oxygenOxazolidineIsoxazolidine
)Oxazoline(OxazoleIsoxazole
Nitrogen/sulfurThiazolidine
Isothiazolidine
)Thiazoline(Thiazole
Isothiazole
Oxygen/oxygenDioxolane
Sulfur/sulfurDithiolane
http://en.wikipedia.org/wiki/Imidazolidinehttp://en.wikipedia.org/wiki/Pyrazolidinehttp://en.wikipedia.org/wiki/Imidazolinehttp://en.wikipedia.org/wiki/Imidazolehttp://en.wikipedia.org/wiki/Pyrazolinehttp://en.wikipedia.org/wiki/Pyrazolehttp://en.wikipedia.org/wiki/Oxazolidinehttp://en.wikipedia.org/wiki/Isoxazolidinehttp://en.wikipedia.org/wiki/Oxazolinehttp://en.wikipedia.org/wiki/Oxazolehttp://en.wikipedia.org/wiki/Isoxazolehttp://en.wikipedia.org/wiki/Thiazolidinehttp://en.wikipedia.org/w/index.php?title=Isothiazolidine&action=edit&redlink=1http://en.wikipedia.org/wiki/Thiazolinehttp://en.wikipedia.org/wiki/Thiazolehttp://en.wikipedia.org/wiki/Isothiazolehttp://en.wikipedia.org/wiki/Dioxolanehttp://en.wikipedia.org/wiki/Dithiolanehttp://en.wikipedia.org/wiki/Dithiolanehttp://en.wikipedia.org/wiki/Dioxolanehttp://en.wikipedia.org/wiki/Isothiazolehttp://en.wikipedia.org/wiki/Thiazolehttp://en.wikipedia.org/wiki/Thiazolinehttp://en.wikipedia.org/w/index.php?title=Isothiazolidine&action=edit&redlink=1http://en.wikipedia.org/wiki/Thiazolidinehttp://en.wikipedia.org/wiki/Isoxazolehttp://en.wikipedia.org/wiki/Oxazolehttp://en.wikipedia.org/wiki/Oxazolinehttp://en.wikipedia.org/wiki/Isoxazolidinehttp://en.wikipedia.org/wiki/Oxazolidinehttp://en.wikipedia.org/wiki/Pyrazolehttp://en.wikipedia.org/wiki/Pyrazolinehttp://en.wikipedia.org/wiki/Imidazolehttp://en.wikipedia.org/wiki/Imidazolinehttp://en.wikipedia.org/wiki/Pyrazolidinehttp://en.wikipedia.org/wiki/Imidazolidine -
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A large group of 5-membered ring
compounds with three heteroatoms also
exists. One example is dithiazoles that
contain two sulfur and a nitrogen atom