Enantioselective bromocycloetherification by Lewis base/chiral Brønsted acid cooperative catalysis.
نویسندگان
چکیده
A binary catalyst system for the enantioselective bromocycloetherification of 5-arylpentenols is described. The combination of an achiral Lewis base and a chiral Brønsted acid affords good enantioselectivities for the cyclization of Z configured 5-arylpentenols to form bromomethyltetrahydrofurans. The constitutional site selectivity is highly dependent upon the aromatic substituent and the configuration of the double bond.
منابع مشابه
Enantioselective Nazarov cyclization of indole enones cooperatively catalyzed by Lewis acids and chiral Brønsted acids† †Electronic supplementary information (ESI) available: For CIF data of (R)-3r, experimental procedures, spectral data, and computational study results. CCDC 1539722. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03183a Click here for additional data file. Click here for additional data file. Click here for additional data file.
Enantioselective control of the chirality of a tertiary a-carbon in the products of a Nazarov cyclization of enones is challenging because the reaction involves an enantioselective proton transfer process. We herein report the use of cooperative catalysis using Lewis acids and chiral Brønsted acids to control the stereochemistry of the tertiary a-carbon in the products of this reaction. Specifi...
متن کاملChiral magnesium(II) binaphtholates as cooperative Brønsted/Lewis acid-base catalysts for the highly enantioselective addition of phosphorus nucleophiles to α,β-unsaturated esters and ketones.
A little cooperation goes a long way: The cooperative Brønsted/Lewis acid-base supramolecular catalysts formed in situ from simple chiral magnesium(II) binaphtholate aqua complexes promoted the highly enantioselective 1,4-hydrophosphinylation of α,β-unsaturated esters with diaryl phosphine oxides and 1,2-hydrophosphonylation of α,β-unsaturated ketones with dialkyl phosphites (see scheme).
متن کاملEnantioselective cooperative triple catalysis: unique roles of Au(I)/amine/chiral Brønsted acid catalysts in the addition/cycloisomerization/transfer hydrogenation cascade.
An enantioselective cooperative process involving the concerted/simultaneous action of three different catalysts i.e. Au(I)/amine/chiral Brønsted acid catalysts has been realized for the synthesis of 2-substituted tetrahydroquinolines from 2-aminobenzaldehydes and terminal alkynes.
متن کاملDirect catalytic asymmetric addition of acetonitrile to N-thiophosphinoylimines.
Direct catalytic addition of acetonitrile pronucleophiles to thiophosphinoylimines is described. Soft Lewis acid-hard Brønsted base cooperative catalysis is crucial to promote this elusive carbon-carbon bond-forming reaction in an enantioselective fashion.
متن کاملTuning the reactivity of Au-complexes in an Au(I)/chiral Brønsted acid cooperative catalytic system: an approach to optically active fused 1,2-dihydroisoquinolines.
An enantioselective cooperative catalysis protocol, utilizing achiral Au(I) complexes and chiral Brønsted acids, has been developed for the synthesis of optically pure fused 1,2-dihydroisoquinolines starting from 2-alkynylbenzaldehydes and 2-aminobenzamides.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Organic letters
دوره 14 1 شماره
صفحات -
تاریخ انتشار 2012