Article · Wikipedia archive · Last revised Jun 20, 2026

2C-B-morpholine

2C-B-morpholine, also known as 2C-B-norphenmetrazine or as 2-(4-bromo-2,5-dimethoxyphenyl)morpholine, is a serotonin receptor modulator of the phenylmorpholine (phenmetrazine) and cyclized phenethylamine groups. It is a ligand of the serotonin 5-HT2A receptor, with an affinity of 20.6 nM and an EmaxTooltip maximal efficacy of 4%. The drug showed 103-fold lower affinity for this receptor than R(–)-DOB and had minimal agonist activity, so for practical purposes would act as an antagonist at the 5-HT2A receptor under most circumstances, despite being technically classified as a partial agonist. 2C-B-morpholine was first described in the scientific literature by Richard Glennon and colleagues by 2004.

Last revised
Jun 20, 2026
Read time
≈ 2 min
Length
358 w
Citations
4
Source
2C-B-morpholine
Clinical data
Other names2C-B-Norphenmetrazine; 2-(4-Bromo-2,5-dimethoxyphenyl)morpholine; 2C-B-MOR; 2C-B-Mor
Drug classSerotonin receptor modulator; Serotonin 5-HT2A receptor ligand
ATC code
  • None
Legal status
Legal status
  • In general Unscheduled.
Identifiers
  • 2-(4-bromo-2,5-dimethoxyphenyl)morpholine
CAS Number
PubChem CID
ChemSpider
ChEMBL
Chemical and physical data
FormulaC12H16BrNO3
Molar mass302.168 g·mol−1
3D model (JSmol)
  • COC1=CC(=C(C=C1C2CNCCO2)OC)Br
  • InChI=1S/C12H16BrNO3/c1-15-10-6-9(13)11(16-2)5-8(10)12-7-14-3-4-17-12/h5-6,12,14H,3-4,7H2,1-2H3
  • Key:OUTZYBJUJMETRJ-UHFFFAOYSA-N

2C-B-morpholine, also known as 2C-B-norphenmetrazine or as 2-(4-bromo-2,5-dimethoxyphenyl)morpholine, is a serotonin receptor modulator of the phenylmorpholine (phenmetrazine) and cyclized phenethylamine groups.1 It is a ligand of the serotonin 5-HT2A receptor, with an affinity of 20.6 nM and an EmaxTooltip maximal efficacy of 4%.1 The drug showed 103-fold lower affinity for this receptor than R(–)-DOB and had minimal agonist activity (with R(–)-DOB having an Emax of 51% in the assay), so for practical purposes would act as an antagonist at the 5-HT2A receptor under most circumstances, despite being technically classified as a partial agonist.1 2C-B-morpholine was first described in the scientific literature by Richard Glennon and colleagues by 2004.1

See also

See also

References

References

  1. Glennon RA, Bondarev ML, Khorana N, Young R, May JA, Hellberg MR, et al. (November 2004). "Beta-oxygenated analogues of the 5-HT2A serotonin receptor agonist 1-(4-bromo-2,5-dimethoxyphenyl)-2-aminopropane". Journal of Medicinal Chemistry. 47 (24): 6034–6041. doi:10.1021/jm040082s. PMID 15537358. One of the first compounds prepared and examined in this investigation was morpholine analogue 2. Compound 2 bears an ether oxygen atom at the benzylic position that is tethered to the terminal amine. However, its 5-HT2A affinity (Ki) 20.6 nM) is 100-fold lower than that of R(-)DOB (Ki) 0.2 nM), and its agonist efficacy in the 5-HT2-mediated calcium mobilization assay is minimal (Table 1). There are several possible explanations for these unfavorable findings. Apart from the molecule possessing a chiral center, the ether oxygen atom might not be tolerated by the receptor and/or the added ethylene "bridge" might not be readily accommodated by the receptor and its presence detracts from affinity. A more plausible explanation, based on prior structure-affinity investigations, is that the secondary amine of 2 contributes to decreased affinity. That is, we have previously shown that addition of small N-alkyl substituents can reduce the 5-HT2A receptor affinity of DOB and DOB-related compounds.16,17
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