Rac-citronellal

As aldehydes, commercially available rac-citronellal and a synthesized aromatic aldehyde and also two commercially available 1,3-diketones, 1,3-dimethylbarbituric acid and Meldrum s acid, were selected [18]. By 2 x 2 combinations of these reactants, four different cycloadducts were generated ([OS 57]). 

P 39] Protocol for single-run processing reservoirs of the 110 Caliper chip were filled with the following solutions [18] 0.10 M solutions of rac-citronellal and a synthesized aromatic aldehyde in methanol/water (80 20) and 0.12 M solutions of 1,3-dimethylbarbituric acid and Mel drum s acid in methanol/water (80 20) with 10% molar catalyst efhylenediamine diacetate (EDDA). 

Figure 6.22 The Synthesis of ( )-Menthol from rac-Citronellal in Two Steps (Route 1a + 2a)...

Crystallization of the crude material without distillation from tert-butyl methyl ether/hexane affords 56% of rac-5, mp 68-70°C, as pale yellow crystals. The submitters obtained a second crop of 1.5 g from crystallization of distilled material mp 68-78°C, starting from citronellal purchased from BASF. The checkers found that dtronellal from Sigma required distillation and gave an impure second crop of 5 only with difficulty. 

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