Squaramide-Catalyzed Asymmetric Intramolecular Oxa-Michael Reaction of α,β-Unsaturated Carbonyls Containing Benzyl Alcohol: Construction of Chiral 1-Substituted Phthalans

Abstract

Organocatalytic enantioselective intramolecular oxa-Michael reactions of benzyl alcohol bearing α,β-unsaturated carbonyls as Michael acceptors are presented herein. Using cinchona squaramide-based organocatalyst, enones as well as α,β-unsaturated esters containing benzyl alcohol provided their corresponding 1,3-dihydroisobenzofuranyl-1-methylene ketones and 1,3-dihydroisobenzofuranyl-1-methylene esters in excellent yields with high enantioselectivities. In addition, enantioenriched 1,3-dihydroisobenzofuranyl-1-methylene ketone could be obtained from the Wittig/oxa-Michael reaction cascade of 1,3-dihydro-2-benzofuran-1-ol.

Dipole‐Transmissive 1,3‐Dipolar Cycloadditions for the Rapid Construction of Polycyclic N‐Heterocycles: Synthetic and Mechanistic Investigations

“…Additional references cited within the Supporting Information. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Access publishing facilitated by University of Otago, as part of the Wiley -University of Otago agreement via the Council of Australian University Librarians.…”

“…Detailed synthetic methods, computational data, X‐ray crystallography data and NMR spectra can be found within the Supporting Information. Additional references cited within the Supporting Information [16–31] …”