# Zlatko Jončev

> Zlatko Jončev is the co-founder and CEO of b-12 (b12 Labs), a Y Combinator S25 startup building AI agents that plan and run chemical synthesis for pharma and biotech. A former national chemistry olympiad champion turned organic chemist, he earned a PhD in Basel, trained as a medicinal chemist at Roche, and did his postdoc in EPFL's Lab of Artificial Chemical Intelligence, where he met co-founder Andres Bran. b-12 aims to shrink early-stage drug discovery from years to months by making molecules that are otherwise hard to make.

- **Role:** Co-Founder & CEO at b-12 (b12 Labs)
- **Organizations:** b-12 (b12 Labs), Y Combinator, EPFL, University of Basel, Roche
- **Nationality:** Serbian
- **Education:** PhD, Organic Chemistry, University of Basel, Postdoctoral researcher, EPFL (Lab of Artificial Chemical Intelligence)
- **Known for:** Co-founder and CEO of b-12, a YC S25 startup building AI agents for molecular synthesis, 3x national chemistry olympiad champion and International Chemistry Olympiad (IChO) competitor for Serbia, Placed 2nd three consecutive years at the Serbian National Chemistry Competition

## Career timeline

- **2018-2022** — PhD in organic chemistry at the University of Basel, working on methodology including atroposelective synthesis
- **2023-2024** — Postdoctoral researcher at EPFL's Lab of Artificial Chemical Intelligence, where he met co-founder Andres Bran and worked on chemical reasoning with LLMs
- **2025** — Co-founded b-12 (b12 Labs) and became CEO; company joined Y Combinator's Summer 2025 batch
- **2025-08** — b-12 launched on YC's Launch YC as a chemistry copilot for pharma and biotech; raised seed funding

## Achievements

- Co-founder and CEO of b-12, a YC S25 startup building AI agents for molecular synthesis
- 3x national chemistry olympiad champion and International Chemistry Olympiad (IChO) competitor for Serbia
- Placed 2nd three consecutive years at the Serbian National Chemistry Competition
- Earned a PhD in organic chemistry from the University of Basel
- Trained as a medicinal chemist at Roche and worked with lab robotics companies
- Co-authored research on chemical reasoning in LLMs for strategy-aware synthesis planning

## Latest updates

- **2025-08** — b-12 launched publicly through Y Combinator's Launch YC as a chemistry copilot for pharma and biotech.
- **2025-08** — Company closed a seed round and continued hiring founding engineers in San Francisco.

## Links

- Website: https://b12-labs.com
- LinkedIn: https://www.linkedin.com/in/zlatkojoncev/
- Twitter/X: https://x.com/ZJoncev

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Profile page: https://yespress.io/zlatko-joncev
Published by YesPress — https://yespress.io
Last updated: 2026-07-31