H3B-5942 free base

    WARNING: This product is for research use only, not for human or veterinary use.

MedKoo CAT#: 408068

CAS#: 2052128-15-9 (free base)

Description: H3B-5942 is a selective, irreversible and orally active estrogen receptor covalent antagonist. In vitro comparisons of H3B-5942 with standard-of-care (SoC) and experimental agents confirmed increased antagonist activity across a panel of ERαWT and ERαMUT cell lines. In vivo, H3B-5942 demonstrated significant single-agent antitumor activity in xenograft models representing ERαWT and ERαY537S breast cancer that was superior to fulvestrant.

Price and Availability

Size Price Shipping out time Quantity
50mg USD 750 2 Weeks
100mg USD 1150 2 Weeks
200mg USD 1850 2 Weeks
500mg USD 2850 2 Weeks
1g USD 3850 2 Weeks
2g USD 6750 2 Weeks
Inquire bulk and customized quantity

Pricing updated 2021-01-27. Prices are subject to change without notice.

H3B-5942 free base, purity > 98%, is in stock. Current shipping out time is about 2 weeks after order is received. CoA, QC data and SDS documents are available in one week after order is received

Chemical Structure


Theoretical Analysis

MedKoo Cat#: 408068
Name: H3B-5942 free base
CAS#: 2052128-15-9 (free base)
Chemical Formula: C31H34N4O2
Exact Mass: 494.2682
Molecular Weight: 494.639
Elemental Analysis: C, 75.28; H, 6.93; N, 11.33; O, 6.47

Related CAS #: 2052132-46-2 (HCl)   2052128-15-9 (free base)    

Synonym: H3B-5942; H3B 5942; H3B5942;

IUPAC/Chemical Name: (E)-4-((2-(4-((E)-1-(1H-indazol-5-yl)-2-phenylbut-1-en-1-yl)phenoxy)ethyl)amino)-N,N-dimethylbut-2-enamide


InChi Code: InChI=1S/C31H34N4O2/c1-4-28(23-9-6-5-7-10-23)31(25-14-17-29-26(21-25)22-33-34-29)24-12-15-27(16-13-24)37-20-19-32-18-8-11-30(36)35(2)3/h5-17,21-22,32H,4,18-20H2,1-3H3,(H,33,34)/b11-8+,31-28+


Technical Data

Solid powder

>98% (or refer to the Certificate of Analysis)

Shipping Condition:
Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.

Storage Condition:
Dry, dark and at 0 - 4 C for short term (days to weeks) or -20 C for long term (months to years).

Soluble in DMSO

Shelf Life:
>3 years if stored properly

Drug Formulation:
This drug may be formulated in DMSO

Stock Solution Storage:
0 - 4 C for short term (days to weeks), or -20 C for long term (months).

HS Tariff Code:

Additional Information

Mutations in estrogen receptor alpha (ERα) that confer resistance to existing classes of endocrine therapies are detected in up to 30% of patients who have relapsed during endocrine treatments. Because a significant proportion of therapy-resistant breast cancer metastases continue to be dependent on ERα signaling, there remains a critical need to develop the next generation of ERα antagonists that can overcome aberrant ERα activity.


1. Puyang X, Furman C, Zheng GZ, et al. Discovery of Selective Estrogen Receptor Covalent Antagonists for the Treatment of ERαWT and ERαMUT Breast Cancer. Cancer Discov. 2018;8(9):1176–1193. doi:10.1158/2159-8290.CD-17-1229

2. Furman C, Hao MH, Prajapati S, et al. Estrogen Receptor Covalent Antagonists: The Best Is Yet to Come. Cancer Res. 2019;79(8):1740–1745. doi:10.1158/0008-5472.CAN-18-3634