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Questions tagged [heterocyclic-compounds]

For questions concerning compounds possessing rings with two or more different types of atoms.

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Is the 4H-Pyran Cation aromatic?

I guess I'm just trying to understand what "cyclic resonance" really means, from all the examples I've come across its always a cyclic system where the pi-electrons go all around the ...
pointlessHumility01's user avatar
6 votes
1 answer
182 views

How is nitrogen the most powerful electron donor in aromatic rings?

In Clayden, page 735, Aromatic Heterocycles 1:Reactions: The other simple five-membered heterocycles are furan, with an oxygen atom instead of nitrogen, and thiophene, with a sulfur atom. They also ...
zxen's user avatar
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1 vote
0 answers
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Rule for which heterocycles are stable?

In medicinal chemistry, is there a rule for which aromatic heterocycles are stable? I've heard that heterocycles with 3+ adjacent nitrogens for example are unstable. However looking in ChEMBL at the ...
Alex I's user avatar
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4 votes
2 answers
655 views

Acidity of metronidazole

Metronidazole has two $\mathrm{p}K_\mathrm{a}$ values: $2.57$ and $15.42.$ The basic group is the imidazole moiety. Does metronidazole have acidic groups?
user139229's user avatar
-1 votes
1 answer
109 views

Mechanism of ring expansion of epoxide

The below transformation is from J. Am. Chem. Soc. 1990, 112, 14, 5583–5601 What does the treatment with lithium anion of ethoxyacetylene in the presence of the lewis acid do to epoxides? How does ...
wayrese's user avatar
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2 votes
0 answers
50 views

Degradation of 4-MeO-Tetrahydrocarbazole

I recently synthesized 4-Methoxy-Tetrahydroxarbazole from 4-MeO-Phenylhydrazine and Cyclohexanone. The product had a off-white color directly after synthesis but was brown after standing over night at ...
arausch's user avatar
  • 31
0 votes
0 answers
56 views

How does a pyrrole react with its C2?

First of all, thank you for reading my question. There is a mechanism I read where the pyrrole reacts with its C2 but I can't draw the arrows so I don't know if I am correct to think that : the ester:...
Mimi's user avatar
  • 71
0 votes
2 answers
248 views

Understanding Hybridisation in Cyclic Compounds

I had a doubt while solving this problem. At first glance of these compounds, I felt that all of them have sp3 hybridisation (for nitrogen), since all of them had 3 bonded pairs and 1 lone pair around ...
Dr Watson's user avatar
-1 votes
1 answer
72 views

Boiling point of 2-methylpyridine is less than that of 3-methylpyridine? [closed]

As I was reading about physical properties of pyridines and substituted pyridines, I came across this: 2-methylpyridine boils at 129°C while 3-methylpyridine boils at 15° higher than 2-methylpyridine ...
Natasha J's user avatar
  • 259
3 votes
2 answers
402 views

Stability of hexazine

I read about a hypothetical compound called hexazine on Wikenigma. It's a 6-membered ring all of whose atoms are nitrogen and they form alternate single and double bonds just similar to benzene. But ...
Proscionexium's user avatar
1 vote
1 answer
228 views

Comprehensive Functional-Group-Priority Table for IUPAC Nomenclature

I can't seem to find a source for a comprehensive list of FG-priorities. I also am not aware of any system to determine the priority for more uncommon FGs. One of the two would be really helpful if ...
Katjuscha's user avatar
-3 votes
1 answer
48 views

synthetic procedure for 1,3,4 thiadiazole from acylhydrazide [closed]

I wanted to synthesize 1,3,4 thiadiazole-2- thiol substituted to benzoic acid the reaction has to happen in such a way that the "acid hydrazide" group of benzoic acid hydrazide has to ...
Dina's user avatar
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0 votes
0 answers
240 views

Mechanism for synthesis of benzofuran

Would someone be able to help me with the mechanism for the synthesis of benzofuran from salicyladehyde (taken from https://en.wikipedia.org/wiki/Benzofuran)? I have got as far as the decarboxylation ...
Holly's user avatar
  • 29
3 votes
2 answers
135 views

Mechanism of Grignard reaction with 2-(thiiran-2-yl)oxirane

What will be the final major product? The answer is 2-(methoxymethyl)-3-(substituted methyl)thiirane: I think $\ce{R}$ of $\ce{RMgX}$ attacks thiirane ring because negative charge on sulfur is more ...
Arpit Raj Choudhary's user avatar
4 votes
1 answer
845 views

Is 2-pyrone an aromatic compound?

I was told by my professor that α-pyrone is not an aromatic compound, but I count two π-electrons as well as one of the lone pairs on oxygen giving six total which would be one of Hückel's $4n + 2$ ...
crisps's user avatar
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4 votes
0 answers
60 views

Purpose of "1H" in naming of substituted heterocyclic compouns [duplicate]

I had a curious thought about the following molecule's name: For such a simple molecule it seemed awfully complicated. From what I gathered, the "[c][1,2]oxaborinin-1-ol" stems from the ...
coloratura's user avatar
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2 votes
1 answer
305 views

Regioselectivity of SN2 reaction on adenine

I found the following question in my examination: I was able to make out from the options that the usage of a base is to remove the supposedly acidic hydrogen from either the Nitrogen $A$ or $B$. ...
Prajwal Tiwari's user avatar
1 vote
1 answer
57 views

Do azaindoles primarily exist in anionic form at physiological pH and act as bases?

I am reading an article where they describe azaindoles (bicyclic pyridine/pyrrole rings) as being basic with $\mathrm{p}K_\mathrm{a} \approx 4.6.$ I suppose at physiological $\mathrm{pH}$ and after ...
Luke McAloon's user avatar
1 vote
1 answer
140 views

Comparing stability of 1,3-dioxolan-2-ide and 1,3-dithiolan-2-ide carbanions

I'd like to compare stability of 1,3-dioxolan-2-ide and 1,3-dithiolan-2-ide carbanions: I think there is no mesomeric or hyperconjugation effect and we should consider inductive effect. Oxygen is ...
TeslaBolt's user avatar
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2 votes
1 answer
1k views

Complete mechanism of benzotriazole synthesis from o-phenylenediamine

Does my suggested mechanism for benzotriazole synthesis look correct? Are the arrows for the cyclization in the right place? Chemdoodle (which I drew this with) makes the curly arrows look a bit weird....
user avatar
3 votes
1 answer
290 views

Why is selenophene aromatic?

According to Wikipedia, The selenophene molecule is flat and aromatic. Being aromatic, it undergoes electrophilic substitution reactions at the 2- or 2,5-positions. These reactions are slower than ...
Sage of Seven Paths's user avatar
3 votes
2 answers
589 views

2-Pyridone tautomer ratio

The following excerpts from different textbooks about keto–enol tautomerism in pyridones seem to be contradictory. Could someone explain which one is right? MARCH’S ADVANCED ORGANIC CHEMISTRY pg-103 ...
Math-Wiz's user avatar
2 votes
0 answers
50 views

Naftiridine hydrogenation

I was reading an article about the synthesis of 1,2,3,4 tetrahydronaphtyridine and I found this image. I don't understand why the major product of hydrogenation is the less substituted and not the ...
Mamelandro's user avatar
5 votes
1 answer
115 views

Regioselectivity in the opening of 3-membered heterocycles

(a) Consider the following reactions : For these two reactions, the nucleophile attacks the less substituted carbon as it is less sterically hindered. (b) Now consider the following reactions : For ...
tardmoe's user avatar
  • 53
3 votes
1 answer
175 views

What molecule is pictured on the cover of Dead Sara's album "Ain't It Tragic?"

An album released today by Dead Sara, titled Ain't It Tragic, has a chemical structure on the album cover. Here's a close-up of that structure: As the structure is partially obscured, it's difficult ...
Zenon's user avatar
  • 157
12 votes
2 answers
566 views

What is the reaction mechanism between acetophenone and ethyl phenylpropiolate to form a 2-pyrone?

I am looking for the mechanism of the following reaction (I believe it is a type of Michael reaction), which is in the textbook "Advanced Organic Chemistry Part B: Reaction and Synthesis" by ...
Richie12138's user avatar
13 votes
1 answer
1k views

Does folic acid contain a benzyl or a phenyl group?

I'm studying for my MCAT currently and I stumbled upon this question. It gives the structure of a folic acid molecule and asks what functional groups can be found within the molecule. I understand ...
Zaid Nour's user avatar
  • 139
4 votes
3 answers
306 views

Finding the major contributing tautomer of 1-(propan-2-yl)-1,2,3,5-tetrahydro-6H-pyrazolo[3,4-b]pyridin-6-one [closed]

I am having a problem generating the correct tautomer for 1-(propan-2-yl)-1,2,3,5-tetrahydro-6H-pyrazolo[3,4-b]pyridin-6-one. I am told by my collaborator that the one I am generating is wrong. I am ...
srinivasan ranga's user avatar
0 votes
0 answers
49 views

Comparing nucleophilic strengths of tetrahydropyran and (2R,6R)-2,6 dimethyltetrahydropyran

Compare the nucleophilic strengths of the following two compounds: According to me it should be the second one, that is, (2R,6R)-2,6-dimethyltetrahydropyran because the methyl groups would exert +I ...
V.G's user avatar
  • 1,251
3 votes
0 answers
119 views

Which atoms in indole possess the greatest amount of electron density?

Presumably the amine acts as an electron donor, but that would suggest extra electron density of the adjacent carbons, making them more shield, which isn't seen in the results in the image below. ...
Pringles Profiteroles's user avatar
-4 votes
2 answers
780 views

What is the double bond equivalence of the following compound?

What is the double bond equivalence of the given compound? The given answer is 14 (8 pi electrons and 6 rings = 14 DBE). But why isn't the lone pair on nitrogen considered? The lone pair on nitrogen ...
Srini's user avatar
  • 109
1 vote
0 answers
56 views

What is the product of reaction between 2‐cyclobutyl‐2‐isopropyl‐1,3‐dioxane and hydrogen with Raney nickel?

I have 2‐cyclobutyl‐2‐isopropyl‐1,3‐dioxane (alcohol protection) and I have to react it with $\ce{H2}$ and Raney nickel, but I don't know what the product would be. I have seen a similar reaction ...
Armando Martinez Blanco's user avatar
0 votes
0 answers
35 views

Examples to show how useful or not useful of dimerization, trimerization, tetramerization and their likes in synthesizing alkenes and other compounds?

this answer shows that dimerization is a synthetic method On wikipedia, 1-octene is showed to made from numerous dimerizations or a tetramerization. When I read that piperazine $\ce{C4H10N2}$ is made ...
Kav's user avatar
  • 242
0 votes
1 answer
67 views

How does NaOH modify pyranodioxins?

I am given the molecule in black which is treated with $\ce{NaOH}$. The product is in blue. Could someone explain the mechanism? All I have so far is that the $\ce{-OH}$ group on the bottom right ...
user256872's user avatar
4 votes
1 answer
389 views

Make pyridine from furfural

Furfural $(\ce{C5H4O2})$ has been used as a feedstock for synthesis. Furfurylamine $(\ce{C5H7NO})$ is made from furfural. Given that industrial manufacturing ammonia is matured, how about combining ...
Kav's user avatar
  • 242
3 votes
1 answer
96 views

How to carry out cyclization of 1‐(2‐methylbutyl)‐2‐nitrocyclohexane?

How the cyclization can take place as there is no other functional group than $\ce{NO2}?$ One way that I can think of is photochemical bromination which occurs selectively at tertiary center which ...
user avatar
9 votes
1 answer
194 views

What's special about the purine scaffold?

Purine is a remarkable substance, given Nature has chosen it as the scaffold for two nucleobases from DNA/RNA: adenine (A) and guanine (G). Its structure also appears in several other substances of ...
ksousa's user avatar
  • 663
0 votes
0 answers
200 views

Why is Tyrian purple called 6,6′-dibromoindigo?

If the two bromines are attached at opposite ends of the molecule, why are they both labelled with a 6? Also, why is 6,6′-dibromoindigo not called 1,1′-dibromoindigo if carbons in a ring are numbered ...
Kurt Hikes's user avatar
  • 1,813
4 votes
1 answer
301 views

Proton NMR splitting in 2-substituted furan

I have recently run proton NMR on 1-(furan-2-yl)ethan-1-ol I synthesised in the lab. My 400 MHz spectrum consists of the following peaks: 7.36 ppm (dd, J = 1.9, 0.9 Hz, 1H) 6.31 ppm (dd, J = 3.3, 1....
FFerreira's user avatar
3 votes
1 answer
1k views

Fischer indole synthesis: significance of choice of acid catalyst

Lately, as a matter of interest, I have been studying sigmatropic rearrangements. I came across the Fischer indole synthesis, whose Wikipedia article states: The Fischer indole synthesis is a ...
Bread's user avatar
  • 43
5 votes
0 answers
115 views

Type of chirality in polycyclic compounds

Ignoring whether or not this molecule could exist, is there a name for this type of chirality? This molecule's mirror image cannot be superimposed on itself but there are no chiral centres. Even ...
hazza_h's user avatar
  • 51
-1 votes
1 answer
946 views

Pyridine: Protic or Aprotic

I know pyridine is a polar aprotic solvent (owing to a permanent dipole generated), but if acidified it forms pyridinium cation. So, does it then function as polar protic solvent?
Solid - NMR's user avatar
3 votes
1 answer
3k views

Why is aniline more basic than pyrrole?

In a question asking to compare the basicity of pyrrole and aniline, the explanation given for aniline being more basic than pyrrole was as follows: Basicity depends on the availability of lone pair ...
Solid - NMR's user avatar
0 votes
1 answer
237 views

Why does magnesium bromide transfers from a carbon atom to nitrogen in piperidine?

In this reaction, why does $\ce{MgBr}$ goes to the $\ce{>NH}$ group and form a bond with nitrogen by removing $\ce{-H}$. Also where does the negative charge go?
Soham Chatterjee's user avatar
4 votes
2 answers
119 views

Acidity of thiamine - how comes hydroxide anion with pK about 15 ionizes thiamine with pK about 18?

Textbooks say removing proton from thiamine's C atom will produce a resonance stabilized carbanion which is hence bioactive. That's OK, but how comes that 1) we abstract the acidic proton with the OH ...
Evgeny's user avatar
  • 49
4 votes
1 answer
263 views

Pyridine synthesis by tin(II) chloride reduction of 5-nitronorbornene

What is the reaction mechanism here? I guess the $\ce{SnCl2}$ reduces $\ce{NO2}$ to $\ce{NH2}$ but then what happens?
lidya's user avatar
  • 51
6 votes
1 answer
6k views

Regioselectivity in Electrophilic Aromatic Substitution of Pyrrole and Indole

If we look into the structures of Pyrrole and Indole, they are very similar. Only Indole has one extra Benzene ring attached to it, i.e. if we attach one Benzene ring to Pyrrole, what we'll have is ...
Soumik Das's user avatar
  • 5,728
5 votes
1 answer
124 views

Stubborn CuAAC reaction as derivatization for ESI-MS

Problem description I have a substance that is extremely non-polar and therefore does not ionize in the ESI source, which makes it impossible to quantify small amounts. The substance contains only two ...
Sam's user avatar
  • 1,257
-1 votes
1 answer
930 views

Friedel-Crafts acylation of furan [closed]

Can furan undergo Friedel–Crafts acylation with benzoyl chloride? Some people say it will have no reaction. Is it true? If so, why cannot it undergo Friedel–Crafts acylation like other ketones?
guest34's user avatar
1 vote
0 answers
120 views

Can Diels-Alder reaction occur using reagents of Robinson annulation?

Robinson annulation seemed somewhat like the Diels-Alder reaction to me, if all ketonic groups were to be represented as enol then cyclohexanone would be like diene and the Michael acceptor as a ...
Swastik's user avatar
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