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Synthesis of C4C5 Cycloalkyl‐Fused and C6‐Modified Chromans via ortho ‐Quinone Methides
Author(s) -
Tangdenpaisal Kassrin,
Chuayboonsong Kanokpish,
Sukjarean Patchaya,
Katesampao Varisa,
Noiphrom Nok,
Ruchirawat Somsak,
Ploypradith Poonsakdi
Publication year - 2015
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201403356
Subject(s) - cycloaddition , chemistry , bromide , catalysis , bicyclic molecule , quinone , palladium , stereochemistry , medicinal chemistry , organic chemistry , combinatorial chemistry
Starting from 3,5‐dimethoxybenzaldehyde, some functionalized 2,3,4‐trisubstituted tricyclic 4,5‐cycloalkyl‐fused and 6‐modified chromans could be prepared via ortho ‐quinone methides ( o ‐QMs)/hetero‐Diels–Alder (HDA) reactions of the appropriate precursors. The bromide at C6 served as a handle for introducing other substituents through palladium‐catalyzed cross‐coupling reactions and other functional‐group transformations. Moderate to high yields (up to 80 %) and diastereoselectivities (up to >99:1) could be obtained under [PtCl 4 ] catalysis. The preferred endo transition state during the cycloaddition reaction played an important role in governing the stereochemical outcomes at C2C3C4. The configurationally fixed E geometry of the bicyclic o ‐QMs influenced the cycloaddition reactions to favor the C2C4 cis relationship.