An Efficient Preparation oftrans, trans-β-Ionylideneacetaldehyde

β-Ionylideneacetaldehyde (1) is an important intermediate in the synthesis of retinoids and carotenoids.1 For our program of synthesis of biologically active retinoids we needed an efficient synthesis of trans, trans-1, both in terms of stereochemical purity and overall yield. Although numerous methods have been devised for the synthesis of 1 1, none of these fit our criteria.