BF3·OEt2‑Catalyzed Unexpected Stereoselective Formation of 2,4- trans-Diallyl-2-methyl-6-aryltetrahydro‑2H‑pyrans with Quaternary Stereocenters

D. SRINIVAS REDDY; BEDURU SRINIVAS; KAVITHA RACHINENI; BHARATAM JAGADEESH; ARIEL M. SAROTTI; DEBENDRA K. MOHAPATRA*

JOURNAL OF ORGANIC CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2021 vol. 86 p. 6518 - 6527

0022-3263

The present manuscript describes a convenient, mild, and highly stereoselective method for the allylation of δ-hydroxy-α,β-unsaturated ketones having a benzylic hydroxyl group at the δ-position using allyltrimethylsilane mediated by BF3·OEt2, leading to 2,4-diallyl-2-methyl-6-aryltetrahydro-2H-pyran ring systems with quaternary carbon stereogenic centers. This represents the first example of a tandem isomerization followed by one C−O and two C−C bond-forming reactions in one pot. The isolation ofTMS-protected lactol as an intermediate from the reaction strongly supports the proposed mechanistic pathway