Enantioselective Synthesis of 1,2-Dihydronaphthalene-1-carbaldehydes by Addition of Boronates to Isochromene Acetals Catalyzed by Tartaric Acid

• Published in: Journal of the American Chemical Society Vol. 137; no. 9; pp. 3233 - 3236
• Main Authors: Luan, Yi, Barbato, Keith S., Moquist, Philip N., Kodama, Tomohiro, Schaus, Scott E.
• Format: Journal Article
• Language: English
• Published: WASHINGTON Amer Chemical Soc 11.03.2015
• Subjects: Acetals - chemistry; Aldehydes - chemical synthesis; Aldehydes - chemistry; Boron Compounds - chemistry; Chemistry; Chemistry Techniques, Synthetic; Chemistry, Multidisciplinary; Naphthalenes - chemistry; Physical Sciences; Science & Technology; Stereoisomerism; Tartrates - chemistry; ACCELERATION; CYCLOADDITION; HYDROGENATION; NAPHTHALENES; DIELS-ALDER REACTIONS; STEREOSELECTIVITY; CHIRAL NAPHTHYLOXAZOLINES; OXOCARBENIUM IONS; DERIVATIVES; ASYMMETRIC ADDITIONS
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.5b00757

Tartaric acid is an ideal asymmetric catalyst as it is abundant, cheap, and environmentally friendly. (+)-Tartaric acid was found to catalyze a novel enantioselective [4 + 2] cycloaddition of isochromene acetals and vinylboronates. A variety of substituted isochromene acetals were tolerated, furnishing the desired dihydronaphthalenes and dihydrobenzofluorene products in good yields. High enantiomeric ratios (up to 98.5:1.5) and excellent diastereoselectivities (all >99:1) were observed employing 10 mol % of (+)-tartaric acid as the catalyst, in combination with 5 mol % of Ho(OTf)(3).