Catalytic applications of keto-stabilised phosphorus ylides based on a macrocyclic scaffold: calixarenes with one or two pendant Ni(P,O)-subunits as ethylene oligomerisation and polymerisation catalysts†
Abstract
Four calix[4]arenes containing either one or two ylidic –C(O)CHPPh3 moieties anchored at p-phenolic carbon atoms were prepared starting from cone-25,27-dipropoxycalix[4]arene (1): 1,3-alternate-5,17-bis(2-triphenylphosphoranylideneacetyl)-25,26,27,28-tetrapropoxycalix[4]arene (12), 1,3-alternate-5-(2-triphenylphosphoranylideneacetyl)-25,26,27,28-tetrapropoxycalix[4]arene (13), cone-5-(2-triphenylphosphoranylideneacetyl)-25,27-dihydroxy-26,28-dipropoxycalix[4]arene (14), cone-5,17-bis(2-triphenylphosphoranylideneacetyl)-25,27-dihydroxy-26,28-dipropoxycalix[4]arene (15). All the