ABSTRACT
This chapter discusses the preparation of novel vitamin A derivatives containing triple bonds and describes novel addition reactions to acetylenic intermediates and/or retinoids. It presents some new acetylenic building blocks that will be the important in future preparative work in this field. The chapter aims to provide tailor-made retinoids carrying substituents in clearly defined positions that influence the electronic and steric nature of retinal in a predictable way. It suggests that addition reactions to acetylenic retinoids constitute a considerable extension of the methods available for the modification of the polyene chain. Both inert and reactive substituents may be introduced by this approach under mild reaction conditions. The "delay" of the addition step to a late stage of the synthesis offers the advantage of employing common intermediates for a vast variety of derivatives. In a step-wise approach every single substituent would require its own building block. The "naked" triple bond function thus serves as a generally usable functional group.
