Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities. β-Substituted aldehydes constitute a very important
Asymmetric michael additions via samp-/ramp-hydrazones enantioselective synthesis of pheromones of the small forest ant and the red wood ant
作者:Dieter Enders、Beatrice E.M. Rendenbach
DOI:10.1016/s0040-4020(01)90603-9
日期:1986.1
<i>Lower Rim</i> Functionalized Chiral Resorc[4]arenes Derived from Citronellal and Carvone
作者:Jochen Mattay、Michael Schiendorfer
DOI:10.1055/s-2005-872108
日期:——
In our work we have provided the lower rim of resorc[4]arenes with stereogenic centers as well as with functional groups. For the synthesis of these lower rim functionalized chiral resorc[4]arenes we have used aldehydes derived from citronellal and carvone. In general, the functional group was introduced into the aldehyde compound prior to the final cyclization step. In the case of substitution of the functional group by chloride ions during the cyclization step under standard conditions (HCl-EtOH, Î), hydrochloric acid was replaced by the conjugated acid of the functional group. Another strategy is the introduction of the iodo group at the lower rim of a resorc[4]arene, which can be easily substituted by good nucleophiles and mild bases without protection of the upper rim.