Abstract: | Previous attempts to synthesize boracyclanes in the medium-ring range (9-, 10-, 11-, and 12-ring members) via cyclic hydroboration of α,ω-dienes have failed. However, their synthesis via the sequential one-carbon homologation of B-methoxyboracyclanes has been achieved utilizing the successive reaction of B-methoxyboracyclanes with in situ generated (chloromethyl)lithium (LiCH2Cl): MeOB(CH2)5 → MeOB(CH2)6 → MeOB(CH2)7 → MeOB(CH2)8 → MeOB(CH2)9 → MeOB(CH2)10 → MeOB(CH2)11. The yields achieved are in the range of 75–85%. In each case the products are identified by conversion via the DCME reaction into the known cycloalkanones. This development provides the first entry into boracyclanes of the strained medium ring range. |