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Chiral Bicyclo[3.3.0]octa‐2,5‐dienes as Steering Ligands in Substrate‐Dependent Rhodium‐Catalyzed 1,4‐Addition of Arylboronic Acids to Enones
Author(s) -
Helbig Sarah,
Sauer Sven,
Cramer Nicolai,
Laschat Sabine,
Baro Angelika,
Frey Wolfgang
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200700232
Subject(s) - chemistry , rhodium , pentalene , bicyclic molecule , enantiomer , stereochemistry , substrate (aquarium) , swern oxidation , enantioselective synthesis , kinetic resolution , diol , diene , catalysis , combinatorial chemistry , organic chemistry , molecule , oceanography , geology , natural rubber , dimethyl sulfoxide
The synthesis of disubstituted chiral diene ligands (3a R ,6a R )‐ and (3a S ,6a S )‐ 10 with a pentalene backbone from the corresponding bicyclo[3.3.0]octa‐1,4‐diones 7 is described. The latter were accessible by enzymatic resolution of the racemic diol rac ‐ 5 and subsequent Swern oxidation. The efficiency of the ligands 10 in the rhodium‐catalyzed 1,4‐addition of arylboronic acids 12 to cyclic and acyclic enones 11 and 15 could be demonstrated. In the case of cyclic enones 11 the enantiomeric diphenyldienes (3a R ,6a R )‐ and (3a S ,6a S )‐ 10a were more selective than the corresponding dibenzyldiene ligands 10b . When acyclic enones 15 were employed this result, however, reversed. Ligands 10a were nearly inactive whereas dibenzyldienes 10b afforded the addition products 16 with enantioselectivities up to 91 %.