3-TRIETHYLSILOXY-1,4-PENTADIENE

Physical properties

bp 140°C; n20D 1.4390.

The Uses of 3-TRIETHYLSILOXY-1,4-PENTADIENE

3-Triethylsilyloxy-1,4-pentadiene is used as a masked vinyl ketone synthon; a precursor for either the diene or dienophile in the intramolecular Diels–Alder reaction.) It may be used to prepare the useful 3-triethylsilyloxypentadienyl anion via metalation with sec-butyllithium (eq 1).
A wide variety of electrophiles may be used and the selectivity is based on kinetics.The method has been used to prepare intermediates for intramolecular Diels–Alder reactions (eqs 4 and 5).

Preparation

3-Triethylsilyloxy-1,4-pentadiene is by silylation of 3-hydroxy-1,4-pentadiene with chlorotriethylsilane.1,2 Other relatives of the title compound are available by silylation with chlorotrimethylsilane2 or t-butyldimethylchlorosilane3 3-Trimethylsilyloxy- 1,4-pentadiene is usually prepared and used in situ. Storage of 3-trimethylsilyl-1,4-pentadiene at ?30°C is recommended. The dianion of the parent 3-hydroxy-1,4-pentadiene can also be prepared.

Purification Methods

Dissolve it in pentane, wash this with H2O, dry (Na2SO4), evaporate, and distil it under vacuum. RF values on Kieselgel 60 are 0.15 (pentane) and 0.60 (*C6H6). [IR, NMR, MS: Oppolzer et al. Helv Chim Acta 64 2002 1981.]