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Dendritic styryl TADDOLs as novel polymer cross‐linkers: First application in an enantioselective Et 2 Zn addition mediated by a polymer‐incorporated titanate. Preliminary communication
Author(s) -
Rheiner P. Beat,
Sellner Holger,
Seebach Dieter
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800702
Subject(s) - chemistry , enantioselective synthesis , polymer , titanate , polystyrene , polymerization , polymer chemistry , catalysis , aryl , molecule , chemical engineering , organic chemistry , ceramic , alkyl , engineering
TADDOLs (α,α,α′,α′,‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols) with dendritic branches attached to the aryl groups and with 8 or 16 peripheral styryl double bonds have been synthesized ( 4 and 5 ). With these compounds, dendritic molecules were employed for the first time as cross‐linkers in a polymerization. The resulting polystyrene was loaded with titanate (Ti(OCHMe 2 ) 4 ) to generate polymer beads incorporating Ti‐TADDOLate centers ( Figs. 1 and 2 ) for enantioselective catalysis (Et 2 Zn addition to PhCHO). Compared with conventionally polymer‐attached, insoluble Ti‐TADDOLates ( cf. 3 ), the new materials have a much higher catalytic activity, rather close to that of soluble analogs ( Fig. 3 ).