Phosphite‐Catalyzed C−H Allylation of Azaarenes via an Enantioselective [2,3]‐Aza‐Wittig Rearrangement
作者:Abdul Motaleb、Soniya Rani、Tamal Das、Rajesh G. Gonnade、Pradip Maity
DOI:10.1002/anie.201906681
日期:2019.10
A phosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio- and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo a stereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C-H functionalization of azaarenes. This method provides
Chirale Alkoxytitan(IV)-Komplexe für enantioselektive nucleophile Additionen an Aldehyde und als<i>Lewis</i>-Säuren in<i>Diels-Alder</i>-Reaktionen
作者:Dieter Seebach、Albert K. Beck、René Imwinkelzied、Silvio Roggo、Anne Wonnacott
DOI:10.1002/hlca.19870700406
日期:1987.7.8
Chiral Alkoxytitanium(iv) Complexes for Enantioselective Nucleophilic Additions to Aldehydes and as Lewis Acids in Diels-Alder Reactions
手性烷氧基钛(iv)配合物对醛和对苯二酸-阿尔德反应中的路易斯酸的对映选择性亲核加成
On the Mechanisms of Enantioselective Reactions Using ?,?,??,?? -Tetraaryl-1,3-dioxolane-4,5-dimethanol(TADDOL)-Derived Titanates: Differences betweenC2- andC1-symmetrical TADDOLs - facts, implications and generalizations
作者:Dieter Seebach、Dietmar A. Plattner、Albert K. Beck、Yan Ming Wang、Daniel Hunziker、Walter Petter
DOI:10.1002/hlca.19920750704
日期:1992.11.11
titanate is involved in the product-forming step, (ii) that the bulky TADDOLate ligand renders the Ti-center catalytically more active than that of (i-PrO)4Ti, due to fast dynamics of ligand exchange on the sterically hindered Ti-center (Table 5, Fig. 3), and (iii) that the role of excess (i-PrO)4Ti is to remove – by ligand exchange – the product alkoxides (R*O) from the catalytically active Ti-center
dialkyl phosphate was synthesized starting from (+)-diethyl tartrate. Its catalytic activity as a chiral Brønsted acid has been examined in the Mannich-type reaction of a ketene silyl acetal with aldimines as a model reaction. The corresponding β-amino acid esters were obtained with high enantioselectivity.