[Michaelmoo]

Ok. So I'm a little confused as to what circumstances an Sp3 hybridized nitrogen is classified as a stereocenter?

Basically, are all of these Nitrogens classified as stereocenters (provided they're not restricted within a ring structure etc)? I know that a solution of one stereoisomer will not show optical rotation (due to N-inversion). But is it still appropriate to say there are R and S configurations about the Nitrogen?

Thanks in advance.

[AWK]

I know that a solution of one stereoisomer will not show optical rotation (due to N-inversion)

This is only crude approximation for beginners.

[Cavillus]

I've found some informations that could help you in solving your doubts:

http://www.rod.beavon.clara.net/chiralit.htm There is a small chapter dealing with nitrogen chirality

From my scholastic rememberings, I can tell you that the only way to lock the inversion of a "normal" amine is to cool it down to really low temperatures.

[AWK]

I've found some informations that could help you in solving your doubts:

http://www.rod.beavon.clara.net/chiralit.htm There is a small chapter dealing with nitrogen chirality

From my scholastic rememberings, I can tell you that the only way to lock the inversion of a "normal" amine is to cool it down to really low temperatures.

The only way to restrain inversion is building proper bulky substituents at nitrogen atom - see oxaziridines, Troger's base. Configutation of trivalent nitrogen atom was determined in late 70s.

[Michaelmoo]

I've found some informations that could help you in solving your doubts:

http://www.rod.beavon.clara.net/chiralit.htm There is a small chapter dealing with nitrogen chirality

From my scholastic rememberings, I can tell you that the only way to lock the inversion of a "normal" amine is to cool it down to really low temperatures.

Thanks for your help. The link made sense.

[Nosterius]

Nitrogen inversion can also be locked in some case, using cyclic structural motifs. Look at the structure of DABCO (1,4-diazabicyclo[2.2.2]octane). It is not chiral in itself, but if the three ethylene units were to bear different substituents, you would end up with a chiral nitrogen center.

[AWK]

Natural compound - quinine shows a chiral nitrogen centre