84433-27-2Relevant articles and documents
Organocatalytic decarboxylative Doebner-Knoevenagel reactions between arylaldehydes and monoethyl malonate mediated by a bifunctional polymeric catalyst
Lu, Jinni,Toy, Patrick H.
, p. 1723 - 1726 (2011)
A bifunctional polystyrene bearing both DMAP and piperidine groups has been prepared and used as an organocatalyst for decarboxylative Doebner-Knoevenagel reactions of arylaldehydes and monoethyl malonate. Isolated yields of the resulting cinnamates were very high, and in all cases only the E-isomer was detected. When a polystyrene catalyst functionalized with only DMAP or piperidine groups was used in these reactions, catalysis was much less efficient. Furthermore, catalysis using a combination of the monofunctional polymers was also less efficient than with the bifunctional polystyrene. Thus, it appears that there is a synergistic effect obtained by co-locating the two different catalytic amine groups on the same polymer backbone. Georg Thieme Verlag Stuttgart · New York.
Polystyrene-Based Deblocking-Scavenging Agents for the 9-Fluorenylmethyloxycarbonyl Amino-Protecting Group
Carpino, Louis A.,Mansour, E. M. E.,Cheng, C. H.,Williams, James R.,MacDonald, Russell,et al.
, p. 661 - 665 (2007/10/02)
Piperazino- and piperidino-functionalized polystyrenes have been examined as deblocking-scavenging agents for the 9-fluorenylmethyloxycarbonyl (Fmoc) amino-protecting group.Both commercial and synthesized polystyrenes have been used as supports.In order to introduce the active functional groups, (chloromethyl)polystyrene 2 was treated with tert-butyl piperazine-1-carboxylate followed by acidic deblocking (HCl/dioxane) or, alternatively, was directly aminated by means of 10 molar excess of piperazine or 1,3-bis(4-piperidino)propane.Compounds 7-9 were examined as cross-linking agents in the preparation of appropriate reagents.Most suitable were reagents prepared from commercial macroreticular resins (XE-305) or those cross-linked via DVT (8).Proof that the DBF liberated in the deblocking prozess was scavenged (partially) by the active secondary amine reagents 4 came from (a) a study of the successful regeneration of an active agent from 5 by treatment with alkali (H2O-dioxane) and (b) liberation of 9-methylfluorene from 5 by hydrogenation (NH4OCHO/Pd-C).
