Facial selectivity in the reaction of dihalocarbenes with 2-substituted 4,7-dihydro-1,3-dioxepines

Recent advances in the syntheses, transformations and applications of 1,1-dihalocyclopropanes

“…65 The structure of the dimerization product of carbenes, which were produced by the reaction of methyllithium with 3,3-dibromo-2,7,7-trimethyl-tricyclo[4.1.1.0]octane, was confirmed by Balci and co-workers. 68 67 The π-facial selectivity of the dihalocyclopropanation of conformationally heterogeneous 2-substituted 4,7-dihydro-1,3dioxepines was studied and the results revealed that π-facial solvation of substrates enhanced endo-addition of dihalocarbene on the side of the distant alkyl substituent.…”

“…67 The π-facial selectivity of the dihalocyclopropanation of conformationally heterogeneous 2-substituted 4,7-dihydro-1,3dioxepines was studied and the results revealed that π-facial solvation of substrates enhanced endo-addition of dihalocarbene on the side of the distant alkyl substituent. 68…”

Synthesis of strained ring systems for bioorthogonal labeling applications

“…Purification on a Redisep Gold Diol column (50 g) using 100% Et2O as eluent and a flow rate of 20 mL/min afforded (E)-2-((5,8-dihydro-4H-1,3-dioxocin-5yl)oxy)ethanol (550 mg, 32%) with a purity of 95%. 77 In an adaption of literature procedures 78 , bromoform (28.6 g, 112 mmol, 1.50 equiv), cetrimonium bromide (2.25 g, 6.1 mmol, 0.08 equiv), Et3N (2 drops) and DCM (20 mL) were mixed and stirred for 20 min. To this solution was added 4,7-dihydro-1,3-dioxepine (7.53 g, 75.3 mmol, 1.00 equiv) and stirring was continued for an additional 10 min.…”