Asymmetric hydrogenation via capture of active intermediates generated from aza-Pinacol rearrangement.
نویسندگان
چکیده
An efficient palladium-catalyzed asymmetric hydrogenation via capture of an active intermediate generated in situ from acid-catalyzed aza-Pinacol rearrangement has been successfully developed, providing efficient access to chiral exocyclic amines with up to 98% ee. Three-, four-, and five-membered cyclic N-sulfonyl amino alcohols are viable substrates. This study opens a new window to the application of asymmetric hydrogenation.
منابع مشابه
Aza-pinacol rearrangement: acid-catalyzed rearrangement of aziridines to imines.
A series of di-, tri-, and tetra-substituted N-tosylaziridines [N-(toluene-p-sulfonyl)aziridines] 1, prepared by aziridination of the corresponding alkenes with N-[(tolyl-p-sulfonyl)imino]phenyliodinane (TsN = IPh), was found to undergo a BF3-catalyzed rearrangement (aza-pinacol rearrangement) under mild conditions to give the corresponding N-tosylimines 2 generally in satisfactory yields.
متن کاملAsymmetric synthesis of 3-spirocyclopropyl-2-oxindoles via intramolecular trapping of chiral aza-ortho-xylylene.
Chiral aza-ortho-xylylene intermediates were efficiently generated from 3-chloro-3-substituted oxindole precursors. The first intramolecular trapping of chiral aza-ortho-xylylene intermediates led to a highly asymmetric synthesis of 3-spirocyclopropyl-2-oxindoles.
متن کاملPd-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols via capture of active tautomers.
An efficient palladium-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols has been developed via capture of the active tautomers. A wide variety of 2,5-disubstituted and 2,4,5-trisubstituted pyrazolidinones have been synthesized with up to 96% and 95% ee, respectively. The hydrogenation pathway includes Brønsted acid promoted tautomerization of pyrazol-5-ols and Pd-catalyz...
متن کاملStereoselective α-fluoroamide and α-fluoro-γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement
BACKGROUND Asymmetric introduction of fluorine alpha-to a carbonyl has become popular recently, largely because the direct fluorination of enolates by asymmetric electrophilic fluorinating reagents has improved, and as a result such compounds are becoming attractive synthons. We have sought an alternative but straightforward asymmetric method to this class of compounds, utilising the zwitterion...
متن کاملSynthesis of Pharmaceutical Intermediates Aiming at Construction of Optically Active Tertiary Alcohols as a Key Technology
In recent years, there has been a large number of what are called standard preparations, such as asymmetric hydrogenation using asymmetric reduction catalysts typified by BINAP and methods using enzymatic hydrolysis, that are reliable from an industrial point of view for the synthesis of optically active secondary alcohols. Furthermore, there are many producers of pharmaceutical intermediates t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of the American Chemical Society
دوره 136 45 شماره
صفحات -
تاریخ انتشار 2014