中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
4-氨基-3-溴三氟甲苯 | 4-amino-3-bromobenzotrifluoride | 57946-63-1 | C7H5BrF3N | 240.023 |
3-氨基-4-硝基三氟甲苯 | 2-nitro-5-(trifluoromethyl)aniline | 402-14-2 | C7H5F3N2O2 | 206.124 |
Substrates that are insufficiently activated towards the hydrated imidazoline ring expansion (HIRE) process have been previously found to deliver exclusively the products of aminoalkyl side-chain ring expansion. Attempted reversal of the process by thermal activation towards HIRE failed. We have found that for such problematic substrates the HIRE-type ring expansion can be effectively achieved by applying lithium hexamethyldisilazide (LHMDS) in toluene. LHMDS is thought to promote intramolecular transamidation, which leads to ring-expanded 10- and 11-membered heterocyclic products in modest to good yields. The process significantly broadens the substrate scope amenable to the HIRE strategy.