Dichloromethane → Cyclopentadiene

Participants

Reaction Steps

Scheme 1 is carried out by treating norbornylene (Aldrich) with (a) K3Fe(CN)6, K2OsO4.2H2O, quinuclidine, K2CO3, t-BuOH:H2O 1:1 to yield a diol intermediate which is then (b) treated with NaIO4, THF:H2O 3:1 at 0° C. to room temperature to yield a dialdehyde; (c) (iPrO)2P(O)CH2C(O)CH2CH2Ph, t-BuOK, THF at 0° C. to room temperature, 2 hr, then the dialdehyde is introduced and the reaction warmed from −78° C. to 4° C. to yield the dieneophile; (d) Diels Alder reaction with (CH3)3Al (0.05 eq.) 10 min, then AlCl3 (0.50 eq.), CH2Cl2 at 0° C., 10 min, then cyclopentadiene (10 eq.) at 4° C. to yield the DA adduct; (e) LiAlH4 (6.0 eq.), THF at room temperature followed by (f) Bz-Cl (3.6 eq.), Et3N (4.0 eq.), CH2Cl2 at room temperature (two steps) to yield the dibenzoate-protected DA adduct; and the ter-cyclopentane scaffold is finally assembled at (g) O3, CH3OH/CH2Cl2 1:1 at −78° C., then NaBH4 (10 eq.) at 0° C. to room temperature.

Provenance & Evidence