(Triphenylphosphoranylidene)acetaldehyde → 1,8-Diazabicyclo(5.4.0)undec-7-ene

Beteiligte Stoffe

Reaktionsschritte

5-Chloroindole-2-carboxaldehyde was prepared starting from ethyl 5-chloroindole-2-carboxylate (7.4 g, 33 mmol) according to the procedure of Preparation 1, obtaining 2 g of a yellow solid, m.p.=208-209° C. The aldehyde (1.2 g, 6.7 mmol) was transformed in (E)-3-(5-chloro-2-indolyl)-2-propenaldehyde through the reaction with (formylmethylene)triphenylphosphorane (2 g, 6.7 mmol) following the procedure described in Preparation 2, obtaining 0.5 g of yellow powder, m.p.=207-209° C. (E)-3-(5-Chloro-2-indolyl)-2-propenaldehyde (0.5 g, 2.4 mmol) and DBU (0.75 ml, 5 mmol) were treated with methyl 2-methoxy-2-(triphenylphosphonium)acetate bromide (2.16 g, 5 mmol) according to the procedure of Example 1A to afford 250 mg (47%) of the title compound, m.p.=166-168° C.

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