Synthesis and Effects of PCP Analogs
A review by John
Q. Beagle
Disclaimer: The
compounds described in this article are powerful drugs. As with
any drug, they should not be ingested without full understanding
of their potential effects. More so than other recreational drugs,
these compounds have the potential to produce dangerously disoriented
states of consciousness. The synthetic procedures presented here
are given for informational purposes only. Some of the steps presented
are potentially dangerous for novice or under equipped chemists,
and some of the compounds described are scheduled drugs, and therefore
illegal to manufacture without proper licensing.
Contents:
Section I. Background information:
- Structure of PCP and its analogs.
- Structures
of other compounds with PCP-like
effects.
- Historical background of PCP.
- Clinical
use and pharmacology.
- Illicit
use and subjective effects.
Section II. Known methods for synthesis
of PCP analogs:
- General
overview of methods:
- Methods I-III. Commonly used routes:
- Method I: Use
of nitrile intermediates such as PCC:
- Overview of the two steps
in the reaction scheme.
- Step 1. Synthesis of PCC-
two possible methods.
- Step 2. Reaction of
PCC with a Grignard reagent.
- Method II:
Use of enamine intermediates:
- General description
and reaction scheme.
- Details of the synthesis
of PCP via an enamine.
- Method III: Use
of imine intermediates:
- Overview of reaction.
- Example: Synthesis
of PCE, the N-ethyl analog of PCP.
- Methods IV-VI. Use of PCA (1-phenyl-cyclohexylamine) intermediate:
- Method IV:
Use of an azide intermediate:
PCA via PCOH (1-phenyl-1-cyclohexanol).
- Method V: The
Ritter reaction:
PCA from PCOH or 1-phenylcyclohexene.
- Method VI:
Use of phenylacetonitrile:
Formation of the cyclohexane ring by alkylation and hydrolysis/rearrangement
to PCA.
- Method VII: Use of N-benzoyl piperidine:
Reaction with organometallic derivative of 1,5-dibromopentane
to produce PCP.
Section III. Synthesis of PCP precursors:
- Cyclohexanone:
by the oxidation of cyclohexanol.
- Piperidine:
by reduction of pyridine.
Section IV. Synthesis of ketamine:
- Overview of synthesis:
- Detailed
procedure:
Section V. Structure-Activity Relationships
(SAR) of PCP analogs:
- Background.
biological evaluation of analogs.
- Structural
modifications of PCP:
- Alterations to the piperidine
ring
- Non cyclic alkyl substituents.
- Cyclic alkylamines.
- Alterations to the aromatic
(phenyl) ring:
- Addition of substituents to the phenyl ring.
- Replacements of phenyl by other aromatic rings.
- Alterations to the cyclohexane
ring:
- Changes in ring size.
- Addition of substituents.
Section VI. Recent Research on PCP
analogs:
- Overview
- Dopamine
receptors:
analogs that bind to a novel site on the dopamine transporter.
- Sigma
receptors:
relationship to PCP pharmacology.
- Opiate
receptors:
analogs with analgesic potential.
- References