Oxygen Heterocycles by the Parham Cyclialkylation

Article abstract of DOI:10.1021/jo00320a032

The addition of butyllithium at -100 deg C to ω-bromoalkyl ethers of o-bromophenol (and its congeners) led to preferential exchange of the aryl bromine at position 2.The resulting organolithium reagents, under suitable conditions, cyclized to afford 2,3-dihydrobenzofurans (6), 3,4-dihydro-2H-1-benzopyrans (13), or 2,3,4,5-tetrahydro-1-benzoxepins (16) in good yields, but less satisfactory results were obtained with the intermediate expected to produce 8-methyl-3,4,5,6-tetrahydro-2H-1-benzoxocin (19). ω-Bromoethyl and ω-bromopropyl ethers of suitable dibromophenols were treated successively with 2 equiv of butyllithium and an electrophile to yield derivatives of 6 and 13.