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Abstract

The electrophilic cyclization of the β-keto ester 43 to the selenide 69 and to the sulfide 87 via different methods, was achieved. These two products were then elaborated in an attempt [diagram not included] to produce a C-2 substituted carotenoid end group moiety 14. The selenium route was discontinued, though, when difficulties in [diagram not included] alkylating the selenide 81 could not be overcome. The sulphur route proved to be more successful when the sulphoxide 98 was [diagram not included] alkylated with two different groups in the C-2 position. However, the ensuing elimination of the sulphoxide in the first [diagram not included] product and the rearrangement of the second product precluded the option of finishing the route to a carotenoid end group moiety 14 at this time. An intermediate suitable for elaboration as a C-3 hydroxy-lated carotenoid end group moiety was also prepared from both the selenium and sulphur routes.