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Abstract
A highly efficient preparation of 2-cyclopentadienyliden-1,3-dioxolane from cyclopentadiene and 2-chloroethyl chloroformate has been achieved. Reaction of two equivalents of sodium cyclopentadienide and KOH with 2-chloroethyl chloroformate at 0.1 M produce the highest yield of this fulvene.
Notes
Because of the increasing attention of this fulvene, the dithiolane 1 has been commercially available since 1996 (Aldrich Chemical Company).
The dioxolane 1 produced different chemoselectivities with dithiolane 2; Hong, B.-C.; Sun, S.-S., unpublished results.
Costs calculated using current Aldrich Chemical Company catalog price (1996–1997). For comparison, a mole of bis(cyclopentadienyl)nickel from Aldrich costs $ 1700; a mole of CF3I gas from Aldrich cost $ 713.
No detailed procedure has been reported for the preparation of fulvene 2 in Scheme 2. However, the reaction is much more complicate and has a significantly lower overall yield than our methodology described (vide infra).
Costs calculated using current Aldrich Chemical Company catalog price (1996–1997). For comparison, 119 moles of cyclopentadiene (distilled from dicyclopentadiene) costs $ 38; a mole of 2-chloro ethyl chloroformate costs $ 51.5.
