Synthesis of (12,13-(13)C2)retinal and (13,14-(13)C2)retinal: a strategy to prepare multiple-(13)C-labeled conjugated systems

Article abstract of DOI:10.1002/recl.19921110307

(12,13-(13)C2)Retinal, (13,14-(13)C2)retinal, (19-(13)C)retinal and (20-(13)C)retinal (1) were prepared in a simple fashion in high yield via a consecutive strategy.The key step is the reaction of a N-methoxy-N-methylamide with an alkyllithium or a Grignard reagent.The preparation of the required N-methoxy-N-methylamide is discussed.In this scheme, only three commercially available (13)C-labeled starting materials (ethyl bromoacetate, acetonitrile and methyl iodide) are sufficient to construct retinals with any possible combination of (13)C labeling in the conjugated tail end.This strategy is applicable to the preparation of many other conjugated systems, such as retinoids, carotenoids and polyenes.