Synthesis of lactams
View Patent ↗Methods for the synthesis of lactams are presented whereby a carboxylic acid of the formula HOOC—OR—NH-LG, wherein OR is an organic moiety and LG is a leaving group, is reacted with an acid, such as an organic acid, in particular a strong acid, and a dehydrating agent, which may be one in the same such as a strong acid anhydride, such that the amount of acid added allows for the desired transformation to take place without the loss of the leaving group (LG) before the cyclization, and recovering the lactam.
1. A process for making a compound of formula Intermediate I(a):
wherein each R 1 independently is aryl, alkyl, cycloalkyl, or haloalkyl, wherein each of said aryl, alkyl, cycloalkyl, and haloalkyl groups optionally includes one or more O or N heteroatoms in place of a carbon atom; or
two R 1 groups on adjacent ring atoms or on the same ring atom together with the ring atom(s) to which they are attached optionally form a 3-8-membered ring; and
y is 0, 1, 2, 3 or 4;
comprising the steps of:
(i) treating a carboxylic acid of formula Intermediate I(b)
with an acid and a dehydrating agent,
wherein LG is a leaving group capable of forming a lactam ring of formula Intermediate I(a), such that the amount of acid added allows for the desired transformation to take place without the loss of the leaving group (LG) before the cyclization, and
(ii) recovering the lactam Intermediate I(a).
2. The process of claim 1 , wherein the leaving group, LG, is lost directly to provide the lactam of Intermediate I(a) without the isolation of any intermediates.
3. The process of claim 1 , wherein the leaving group, LG, remains on the lactam prior to step (ii).
4. The process of claim 1 , wherein the acid is trifluoroacetic acid.
5. The process of claim 1 , wherein the dehydrating agent and the acid comprise an acid anhydride.
6. The process of claim 1 , wherein the dehydrating agent and the acid comprise an acid anhydride composed of two molecules of the same acid.
7. The process of claim 1 , wherein the dehydrating agent is a carbodiimide-based agent, an aminium-based agent, a phosphonium-based agent, or a uronium-based agent.
8. The process of claim 5 , wherein the acid anhydride is trifluoroacetic anhydride.
9. The process of claim 6 , wherein the two molecules of the same acid are selected from trihaloacetic acids, dihaloacetic acids, and optionally substituted aryl/heteroaryl acid anhydrides.
10. The process of claim 7 , wherein the carbodiimide-based agent is DCC or EDC.
11. The process of claim 7 , wherein the aminium-based agent is HBTU, TBTU, HATU, or HTCU.
12. The process of claim 7 , wherein the phosphonium-based agent is BOP, PyBOP, PyAOP, or PyBroP.
13. The process of claim 7 , wherein the uronium-based based agent is TSTU, TOTU, or TPTU.
14. The process of claim 7 , wherein the dehydrating agent is DEPBT, CDI or T3P.
15. The process of claim 9 , wherein the trihaloacetic acid is trifluroacetic acid.