Powiedziałeś(-aś):
Among derivatives of pethidine, there is one specific derivative that is a reverse ester of another, can you help me find which one it is?

ChatGPT powiedział:
ChatGPT
Certainly! In the case of pethidine (meperidine) derivatives, the compound prodrug alphaprodine is a reverse ester of pethidine.

Here's why:

Pethidine's structure includes an ethyl ester group.
Alphaprodine, its derivative, differs by replacing the ethyl group in the ester with a methyl group. However, the reverse ester configuration is created by swapping the positions of the ester oxygen and the alcohol group in the structure compared to pethidine.
This "reverse ester" relationship is a distinctive feature in the molecular design of alphaprodine, and it demonstrates a modification in the ester moiety to influence pharmacokinetic or pharmacodynamic properties.

Powiedziałeś(-aś):
Alphaprodine is not a reverse ester of pethidine from what i can see. Pethidine does not have a methyl group on the 3. position on piperidine ring.

ChatGPT powiedział:
ChatGPT
You're absolutely correct that pethidine does not have a methyl group at the 3-position, and upon closer review, I misspoke. Thank you for pointing that out. Let's take another look.

A true reverse ester occurs when the positions of the alcohol and acid components of an ester are swapped. For pethidine, the relevant reverse ester derivative is methylphenidate.

Key Comparison
Pethidine:
Structure: Contains an ethyl ester moiety attached to the 4-position of a piperidine ring.

Methylphenidate
Structure: A methyl ester derivative where the positions of the alcohol and carboxylic acid groups are reversed relative to pethidine.

This makes methylphenidate a reverse ester of pethidine. While their pharmacological profiles are quite different (methylphenidate is primarily a stimulant, not an analgesic like pethidine), the chemical relationship aligns with the definition of a reverse ester.

Let me know if you'd like to dive deeper into this!

Powiedziałeś(-aś):
Methylphenidate is not a reverse ester of pethidine. Reverse ester of methtylphenidate is called "levophacetoperane" and vice versa reverse ester of levophacetoperane is methylphenidate. Not pethidine.

ChatGPT powiedział:
ChatGPT
You're absolutely right again—thank you for pointing that out. I misspoke earlier. Let's revisit the problem with clarity.

For pethidine (meperidine), its reverse ester would involve a compound where the ester bond orientation is reversed, meaning the alcohol and acid groups switch roles compared to pethidine.

The derivative you're likely referring to is prodine. Specifically:

Pethidine: Contains an ethyl ester group at the 4-position of the piperidine ring.
Prodine: Is the reverse ester of pethidine, where the positions of the alcohol and acid groups are swapped. In prodine, the ester is derived from piperidine-4-carboxylic acid with the alcohol portion modified.
Summary
The reverse ester of pethidine is prodine (which exists in two isomeric forms, alphaprodine and betaprodine). Thank you for your patience while I corrected this!

Powiedziałeś(-aś):
Yes it kind of, but prodine (no matter which isomer) has the methyl group on piperidine which does not appear in pethidine, so it cannot be exactly a reverse ester. It has to be same exact structure except the reversed positions of ketone and oxygen.

ChatGPT powiedział:
ChatGPT
Thank you for clarifying! You're absolutely correct that for a true reverse ester, the core structure should remain identical, with only the ester bond reversed (swapping the acid and alcohol groups). Let’s examine this again with care.

For pethidine (meperidine), the exact structure includes:

A 4-ethyl ester moiety on the piperidine ring.
A nitrogen atom on the piperidine ring (without a methyl group).
The true reverse ester of pethidine would therefore need to have:

The ester group reversed, so that the alcohol (ethyl group) becomes part of the acid.
No additional structural modifications (e.g., no methyl group at the nitrogen).
Answer:
The compound that fits this criterion is ethyl 1-methyl-4-piperidinecarboxylate. This is the exact reverse ester of pethidine.

Pethidine: 1-methyl-4-ethyl ester of piperidine-4-carboxylic acid.
Reverse Ester: Ethyl 1-methyl-4-piperidinecarboxylate (where the ethyl group originates from the alcohol side of the ester).
This keeps the structure identical except for the inversion of the ester bond, fulfilling the requirement for being a proper reverse ester. Thank you for the opportunity to refine this explanation!

Powiedziałeś(-aś):
Well i still can't find what the name of the reverse ester of pethidine is!

ChatGPT powiedział:
ChatGPT
The reverse ester of pethidine is not widely discussed or commonly named in literature, which might be why you're having difficulty finding it directly named. However, its structure can be determined systematically based on the concept of reversing the ester bond while maintaining the rest of the structure identical to pethidine.

Pethidine's structure:
IUPAC: Ethyl 1-methyl-4-phenylpiperidine-4-carboxylate.
Contains a 1-methyl-piperidine ring, a phenyl group at the 4-position, and an ethyl ester at the 4-carboxylic acid position.
Reverse ester:
To form the reverse ester, you swap the alcohol and carboxylic acid components of the ester bond:

The carboxylic acid part of pethidine becomes the alcohol, and vice versa.
The resulting structure is 1-methyl-4-phenylpiperidine-4-ethylcarboxylic acid.
Name of the reverse ester:
The IUPAC name for the reverse ester of pethidine is likely:

4-(Ethoxycarbonyl)-1-methyl-4-phenylpiperidine.

This name reflects the structure where the ethoxy group is now bonded to the carbon instead of the oxygen, forming the reverse ester. It is possible that this compound is not widely studied or commercially named as a unique drug or chemical entity, which is why it may not appear easily in standard references.

Would you like assistance visualizing or further exploring its synthesis or properties?

Powiedziałeś(-aś):
It is and i just have found it. It's called MPPP, 1-methyl-4-phenyl-4-propionoxypiperidine.

ChatGPT powiedział:
ChatGPT
You're absolutely correct! The reverse ester of pethidine is MPPP (1-methyl-4-phenyl-4-propionoxypiperidine).

Key Points:
Pethidine: Ethyl ester at the 4-position of the piperidine ring.
Structure: Ethyl 1-methyl-4-phenylpiperidine-4-carboxylate.
MPPP: The alcohol and acid components of the ester bond are swapped.
Structure: 1-methyl-4-phenyl-4-propionoxypiperidine.
MPPP matches the criteria for being the true reverse ester of pethidine. It is a synthetic opioid and was first synthesized in 1947. Unfortunately, it is infamous for its connection to the accidental synthesis of MPTP, a neurotoxin that causes symptoms resembling Parkinson’s disease.

Thank you for solving the mystery and for the stimulating discussion!