Organocatalytic chemoselective asymmetric N-allylic alkylation of enamides

Abstract

The first Lewis base-catalysed chemoselective asymmetric N-allylic alkylation of enamides with Morita-Baylis-Hillman carbonates has been developed, which affords multifunctional products in moderate to high enantioselectivity (up to 92% ee).

Organocatalytic asymmetric transformations of modified Morita–Baylis–Hillman adducts

“…On the other hand, N-allylic enamides 64 can undergo a concerted aza-Cope rearrangement at elevated temperatures and chiral ketones 66 with wellretained enantiopurity could be afforded in a one-pot procedure (Scheme 24). 35 The modified Cinchona alkaloid-catalysed N-allylic alkylation with MBH carbonates 2 was further developed by Cheng and co-workers. Benzophenone imine 67 was found to be a competent ammonia equivalent and exhibited good reactivity towards a wide range of MBH carbonates 2 under the catalysis of [DHQD] 2 AQN.…”

Organocatalytic enantioselective methodologies using Morita–Baylis–Hillman carbonates and acetates

“…In 2011, Chen and co-workers also reported a highly enantioselective N-allylic alkylation of enamines with MBH carbonates. 29 The chemoselective N-alkylation could be realized via deprotonation by the in situ generated tert-butoxy anion of the acidic proton of the enamide. The deprotonated enamide reacted with the MBH carbonates via a S N 2 0 -S N 2 0 pathway catalyzed by (DHQD) 2 AQN (IX) resulting in multifunctional enamides in good yields and with good enantioselectivities (Scheme 25).…”

RegioselectiveS-allylation of thiols with cyclic Baylis–Hillman acetates

“…[4][5][6] In this context, a large number of synthetic methods involving carbon, nitrogen, and oxygen nucleophiles have been previously reported. [7][8][9][10][11][12][13][14][15] However, synthetic approaches, using transition metal-free or transition-metal-catalyzed S-allylation of thiols, are not yet well-developed, [16] presumably due to the poisoning of metal catalysts by coordinating-sulfur [17][18][19] and the low selectivity of such procedures. [20,21] Therefore, a clean and economical S-allylation is still a very attractive goal for the construction of carbon-sulfur bonds, especially in functionalized allylic compounds such as Baylis-Hillman (BH) adducts.…”