Amberlyst-15 in organic synthesis

Reviews and Accounts ARKIVOC 2012 (i) 570-609 O NH2 HN O Amberlyst-15 Amberlyst-15 OH neat, rt, 10 min OH OH OH neat, rt, 8 min + (Boc)2O ; N + (Boc)2O H o 96% NBoc O 92% 39 40 41 42 Scheme 21 11.2 Deprotection of acetals, thioacetals, acetates and Boc-protected amines The importance of the deprotection of acetals,23a-c thioacetals,24a-c acetates25a-c and Boc-protected amines26a,b to their corresponding functional groups in multi-step organic synthesis can not be overstated. Amberlyst-15 has been shown to catalyze such reactions efficiently to give good yields of the deprotected products. 11.2.1 Deacetalization reaction Coppola demonstrated that Amberlyst-15 can be used as an excellent catalyst for the hydrolysis of acetals or ketone acetals to the corresponding carbonyl derivatives (Scheme 22).27a Thus, when a solution of acetal 43 in acetone, containing water is added to Amberlyst-15 and the mixture is stirred at room temperature for 10 min the corresponding carbonyl compounds 44 was produced in high yield. OCH3 O Amberlyst-15, acetone, water, rt, 10 min OCH3 R R 97-99% 43 44 R= H, CH3 Scheme 22 Page 584 ©ARKAT-USA, Inc.