Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols
作者:Chi-Tung Yeung、Wesley Ting Kwok Chan、Wai-Sum Lo、Ga-Lai Law、Wing-Tak Wong
DOI:10.3762/bjoc.15.92
日期:——
New chiral atropisomeric biphenyl diols 3, 4 and 6 containing additional peripheral chiral centers with different steric bulkiness and/or electronic properties were synthesized. The X-ray crystal structure of 3 shows the formation of a supramolecular structure whereas that of 6, containing additional CF3 substituents, shows the formation of a monomeric structure. Diols 1–6 were found to be active organocatalysts
Planar-Chiral Bis-silanols and Diols as H-Bonding Asymmetric Organocatalysts
作者:Christine Beemelmanns、Ralph Husmann、Daniel K. Whelligan、Salih Özçubukçu、Carsten Bolm
DOI:10.1002/ejoc.201200548
日期:2012.6
enantiopure planar-chiralbis-silanols and bis-carbinols were obtained in good yields. The catalytic activities of the bis-silanols were analyzed by monitoring HDA reactions between Rawal's diene and aldehydes by in situ IR spectroscopy and comparing the resulting data with those obtained in catalyses with the corresponding bis-carbinol derivatives. The results show for the first time that planar-chiral bis-silanols
The enantioselective hetero-Diels-Alder reaction of Danishefsky’sdiene with simple aromatic and aliphatic aldehydes is catalyzedby chiral tridentate Schiff base-chromium(III) complexes.In many cases, 2,3-dihydropyran-4-ones are obtained in good yields(up to 99%) and high enantioselectivities (up to 97%).