Silicon-Assisted Ethoxycarbonylmethylation ofN-Methylquinolinium and Isoquinolinium Iodides
摘要:
A new regioselective route to 2-ethoxycarbonylmethyl- 1,2-dihydro-N-methylquinolines and 1-ethoxycarbonylmethyl-1,2-dihydro-N-methylisoquinolines is described starting from methylquinolinium or -isoquinolinium iodides and commercially available ethyltrimethylsilyl acetate (ETSA). The methylene carbanion was generated by fluorodesilylation using caesium fluoride. On exposure to air, the ethoxycarbonylmethyl adducts were oxidised, leading to the corresponding alkylidene derivatives 4 and 5, whereas 2a in solution led slowly to its regioisomer 6a.
10-Methylacridinium perchlorate (1) effectively promotes various reactions of ketene silyl acetals: aldol and Michael addition products are obtained with aldehydes, ketones, acetals, and α-enones. The reactions exhibit unusual dependency upon 1, namely the yields are excellent when a catalytic amount of 1 is employed whereas no desired products are accessible by the use of 1 in a stoichiometric quantity