Preparations du Trans‐P‐Methoxyphenyl‐1‐propene‐1‐14C‐3 (Trans Anethole 14C‐3) et du trans‐anethole (Noyau 14C‐U)

Abstract

AbstractMethyl iodide 14C is reacted with lithium p‐methoxy phenylacetylenide to give with a 85% yield 1‐p‐methoxy‐phenyl‐1‐propyne‐3‐14C.Reduction of the latter with LiAlH4 leads to a mixture of trans anethole‐3‐14C (85%) and cis anethole (15%) with a 55% yield. After preparative gas chromatography pure trans anethole‐3‐14C is isolated with an overall yield of 20% based on methyl iodide 14C.Benzene 14C (U) is brominated into bromobenzene 14C (U) which by copper catalysed alcaline hydrolysis gives phenol 14C (U). Methylation of the latter leads to anisole 14C (U).Gattermann reaction with the latter gives a mixture of o‐and p‐méthoxy‐benzaldehyde 14C (U) in a 80% yield from which pure para isomere is isolated by colwmn chromatography with a 42% yield based on anisole 14C (U). Treated with ethyl magensium iodide p‐methoxybenzaldehyde leads to 1‐p‐methoxy‐phenyl‐1‐propanol (ring 14C‐U) the dehydration of which by heating with Al2O3 gives a mixture of trans anethole (ring 14C‐U) (80%) and cis anethole (ring 14C‐U) (20%). After preparative gas chromatography pure trans anethole (ring 14C‐U) is isolated with an overall yield of 5% based on barium carbonate 14C.