Diels‐Alder‐Reaktionen von 2,3‐Bis(trimethylsilyloxy)‐1,3–dienen

The first synthesised examples of di-siloxy-substituted cyclopentadienyl zirconocenes, their synthesis, structure and activity in ethylene polymerisation

“…The second siloxy group was induced according to the slightly modified literature method with high yields by Hansson [19,20]. Although 3b-c are novel compounds, 2,3-bis-trimethylsiloxy-cyclopenta-1,3-diene 3a has previously been synthesised by Reetz [24] and 2,3-bis-trimethylsiloxy-1-methyl-cyclopenta-1,3-diene has been synthesised by Hansson [19]. Reetz describes 3a as sensitive for Diels-Alder reactions during the distillation step or when synthesised by an alterative method to have a tendency to polymerise on storage.…”

“…The molecular structures of 5a and 5b are reported. A few reports exist regarding 1,2-disiloxy-substituted- [19][20][21][22][23][24] and 1,3-di-siloxy-substituted- [25,26] cyclopentadienes, but no previous example of a metallocene with such cyclopentadienyl ligands can be found in the literature.…”

Tilcotil® Studies. Part 2. [4 + 2] Additions with Isothiazol‐3(2H)‐one 1,1‐Dioxide

“…A corresponding 5,7-dihydroxy derivative would in all probability not be sweet (for structure-taste relationship of various saccharin and acesulfam derivatives, see [23]). [25], without doubt the least reactive of this series, still combines with many electron-deficient dienophiles in Diels-Alder fashion [16] [26]. It is preferably prepared by direct silylation of butane-2,3-dione [27].…”

2,3-Bis(trimethylsilyloxy)-1,3-cyclohexadiene

“…2 Alternatively, with the bulky silicon base Sodium Hexamethyldisilazide, self-condensation was less problematic (eq 2). 3 The bis(silyloxy)diene can also be directly prepared under less basic conditions from the dione using Me 3 SiOTf/NEt 3 (eq 2). 68% Reetz has shown that 2,3-bis(trimethylsilyloxy)-1,3cyclohexadiene, an electron-rich diene, reacts readily in a Diels-Alder fashion with a variety of activated dienophiles (eq 3).…”

“…Although such reactions have not been described for the cyclohexane-1,2dione derivatives, structurally related species may be desilylated to regenerate the 1,2-dione (eq 6). 3 The high electron density in the bis(1,2-silyloxy)-1-alkenes makes them suitable educts for inverse electron demand Diels-Alder reactions (eqs 7 and 8). 8, 9 Finally, the silyl enol ether can undergo normal electrophilic addition to imines, leading to α-hydroxy carbonyl compounds (eq 9).…”