New ethylzinc reagents with remarkable properties in palladium-catalyzed zinc-ene reactions
作者:Wolfgang Oppolzer、Fridtjof Schröder、SÖNke Kahl
DOI:10.1002/hlca.19970800705
日期:1997.11.3
Pd-Catalyzed Zn-ene allylic olefinations with the new ethylzinc reagents EtZnOSO2CF3 (4) and EtZnOC(O)CF(MeO)CF3 (5) in CH2Cl2 showed an unexpected trans-selectivity in the ring closure to cyclopentane derivatives (see Scheme 2 and Table 1). This strong trans-selectivity is in contrast with the corresponding known Zn-ene reaction using Et2Zn in Et2O which shows a high cis-selectivity (Table 1). The