Try Marvin sketch (Msketch) by ChemAxon. I think they have a Mac version and it might be free.

Yes it is free but they have several disadvantages (f.ex. advanced stereochemistry and export to eps files), and certainly they are not as perfect as ChemDraw.

Look at the ACDlabs web page: http://www.acdlabs.com/support/mac.php

ChemDoodle. This is a great tool for chemical sketching and publishing. The single-user license is priced at ~70 USD, but there is a free trial for Mac OS available on their website. I'm very satisfied with this package - it's light, fast, intuitive and feature-rich (e.g. NMR/MS prediction and data processing/editing, built web components, a lot of widgets, etc.)

I have always liked the freeware version of ChemSketch

My mistake, I was sure they had a Mac version. After checking into it they just suggest using an emulator.

I would recommend using BKChem. It's open source and has many of the features found in chemdraw. bkchem.zirael.org/

I use Marvin sketch on linux and it is very usefull, there is a mac version available but i don't use it... so i can't say if this is the same.

MarvinSketch (and the rest of the Chemaxon suite) are written in Java, so there shouldn't be much difference in functionality between platforms. I've always been happy with it on the Mac.

For open source software, there's also JChemPaint (http://jchempaint.github.com/) and molsKetch (http://molsketch.sourceforge.net/). I don't have as much experience with them.

I'm a bit picky about structure drawing programs. Chemdraw is good, the only other one I like is chemsketch but as far as I know chemdraw is the only one with a mac version (without emulation). After using several of the alternatives through the years I know how frustrating they can be and if you're using them often for your work if you're anything like me they'll really slow you down.

To be honest I'd say stump up the money for chemdraw or run the free version of chemsketch via an emulator - I know its not what you wanted to hear but I really think you'll save yourself some headaches.

You can try Chemdoodle.

I agree with Eliot.

ChemDoodle (http://www.chemdoodle.com) is definitely the best alternative to ChemDraw. It much cheaper, but as powerful as you need. I suggest you to visit the website and try the free trial version.

Use MarvinSketch from Chemaxon, greta and free for academics ;)

I always used ChemDraw for Mac so far but I will give MarvinSketch a try. There is an app called OSRA 2 which is not free but can be compiled from source via macports or fink.

http://sourceforge.net/apps/mediawiki/osra/index.php?title=Download

I have used ChemDoodle but I am back to ChemDraw. I am amazed no good app has been made to deal with this problem. You might try Schrodinger's Maestro program. It runs on a Mac and can do 2-d as well as 3-D images. It is easy to build molecules and it has a number of feature for evaluation of structures. If you are in academics it is free.

schrodinger.com

Use ChemAxon product "ChemSketch". This is open source and works on JAVA.  

Thanks a lot Ahmad! MarvinSketch is amazing! Real lifesaver!

ChemDoodle is also pretty nice. On the other hand few years ago, I tested some of this tools and then none could compete with ChemDraw. Maybe situation has changed nowadays.

Is it really free? Could you send the link? I did find it...

Thanks a lot

1.Marvin [https://www.chemaxon.com/products/marvin/]

2. Avogadro [http://avogadro.cc/]

3. BKChem [http://bkchem.zirael.org/download_en.html]

4. MollyCule [http://mollycule.graemebell.net/]