5-Trimethylsilyl-l,3-pentadiene

The effects of the second double bond have also been examined. As might be expected from the case of styrene, the reaction of ( )-l, 3-decadiene and 2-( -hexy 1)-1,3-butadiene was very sluggish and did not proceed detectably over 12 h. Although 1,4-pentadiene itself has not yet been tested, ( )-5-methy1-1,4-undecadiene, ( )-4-( -butyI)-1,4-nonadienc, and (Z)-4-(trimethylsilyl)-l,4-nonadiene have provided the desired 2-methylated alcohols in 79, 84, and 69% yields, respectively [15]. Similarly, ( )-6-methyl-l,5-dodecadiene and ( )-5-(n-butyl)-... 

Rearrangement processes of alkyltitanocene dichlorides that occur under electron impact have been investigated using deuterium labelling. A novel type of zirconium-mediated coupling reaction of alkynes with vinyl bromide to afford 2,3-disubstituted dienes has been reported (see Scheme 105), and an inter-intramolecular reaction sequence has been proposed for the observed formation of vinylcyclohexadienes and/or methylenecycloheptadienes from the copper-catalysed reaction of zirconacyclo-pentadienes with allylic dichlorides. The essential step in these processes appears to be transmetallation of the zirconium-carbon bond of the zirconacyclopentadiene to produce a more reactive copper-carbon bond. New phosphorus heterocycles, e.g. (417), have been constructed by the thermal rearrangement of a [l,4-bis(trimethylsilyl)->/ -cyclooctatetraene]- ,3,5-triphospha-7-hafhanorbomadiene complex (416). 

A solution of [f/ -l,3-bis(trimethylsilyl)cyclopentadienyl]lithium is prepared in situ, using the procedure described in Section 33.A, from butyllithium (IS.OmL of a 1.5 M solution in C6H14, 29 mmol) and bis(trimethylsilyl)cyclo-pentadiene (5.89g, 28 mmol) in THF (lOOmL). This solution is added dropwise during h to a stirred, cooled (0°Q solution of uranium(IV) chloride (5.45g, 14mmol) in THF (lOOmL). The mixture is stirred at 25°C for 12h. Removal of the solvent at 25 °C and lOtorr affords a sticky brown residue this residue is warmed to 60°C at 10 torr. The brown involatile solid is extracted into warm toluene (100 mL), and the extract is filtered. The brown filtrate is concentrated (to 50mL), then cooled to — 30°C to yield large orange-brown crystals of [UCp"2 CI2 ] (2). Yield 6.1 g (60%). Two further crops of crystals are obtained from the mother liquor (total yield, 90%). For its characterization, see Table I. 

Related Reagents. Allyllithium Crotyllithium 9-[l-(Trimethylsilyl)-2( )-butenyl]-9-borabicyclo[3.3. IJnonane 5-Trimethylsily 1-1,3-pentadiene... 

Hydroxy-4-methoxy-4-methyl-l-trimethylsilyl- E21b, 1213 [R-CHO -> R-CH(OH)-C(OR)(CH3) — C4H9] 1,2-Pentadien l-(l-Ethoxy-ethoxy)-4-methyl-l-trimethylsilyl- El 5/3, 3003 [En-H - En-CH(CH3)2] Peroxid (1,1-Dimethyl-propyl)-(1,1 -dimethyl-3-trimethylsilyl-2-propinyl)- E13/1, 360 (OH - O-OR)... 

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