Stereoselective synthesis of carane-based aminodiols as chiral ligands for the catalytic addition of diethylzinc to aldehydes

Stereoselective Synthesis and Modelling‐Driven Optimisation of Carane‐Based Aminodiols and 1,3‐Oxazines as Catalysts for the Enantioselective Addition of Diethylzinc to Benzaldehyde

“…As the ring closure of monoterpene‐based aminodiols with rigid structures enhances their catalytic potential, we incorporated one of the hydroxy groups of compounds 15 – 17 into a condensed 1,3‐oxazine or spiro‐oxazolidine ring. When the aminodiols 15 – 17 were reacted with formaldehyde at room temperature, the 1,3‐oxazines 19 – 21 were obtained by highly regioselective ring closures, similarly as for the regioisomeric carane‐based analogues (Scheme ) …”

“…The enantiomeric purities of the 1‐phenyl‐1‐propanols ( S )‐ 23 and ( R )‐ 23 were determined by GC on a CHIRASIL‐DEX CB column by using literature methods . For the aminodiols 14 – 18 , the moderate to good ( R ) selectivity observed (Table ), exceeded that observed when the regioisomeric aminodiols were applied . The best result (86 % ee ( ee =enantiomeric excess), ( R ) selectivity) was observed in the case of the N ‐( S )‐1‐phenylethyl‐substituted aminodiol 16 .…”

Regio‐ and Stereoselective Synthesis of Bicyclic Limonene‐Based Chiral Aminodiols and Spirooxazolidines

“…Given that we previously clearly demonstrated that substituents on the nitrogen atom of aminodiols definitely influenced the efficiency of their catalytic activity, aminodiol library 9 – 12 was prepared by aminolysis of epoxide 7 with primary amines and lithium perchlorate as the catalyst (Scheme ) …”

“…The results are presented in Table . The enantiomeric purities of propanols ( S )‐ 27 and ( R )‐ 27 were determined by GC on a CHIRASIL‐DEX CB column by using literature methods . Low‐to‐good enantioselectivities were observed.…”

Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by Chiral O,N,O‐tridentate Phenol Ligands Derived From Camphor

“…Therefore, the development of efficient methods for the preparation of optically pure secondary alcohols has received much attention, and the asymmetric addition of diethylzinc to aldehydes is one of the most effective approaches for preparing them. 7,8 Although many bidentate chiral ligands have been prepared and tested in the catalytic asymmetric addition of diethylzinc to aldehydes, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] the development of efficient tridentate ligands have not been studied extensively. Tridentate ligands should confer more rigidity to the reactive zinc chelate catalyst structures, thereby allowing better discrimination between the two enantiotopic faces of an aldehyde in the transition state complex.…”