Synthesis grandisol enantiomers

The foregoing prospectus for the chrysanthemic acid synthesis represents enantioselective transformations of the first kind (Scheme 39, equation i). The second kind (equation ii) is represented by studies directed toward the (+) and (—) grandisol enantiomers (183). 

The use of these cyclobutano sugars has been developed for the synthesis of natural products such as grandisol [47]. Both enantiomers of this pheromone are available by 2 + 2 photoaddition of ethylene to methyl hex-2-enopyranosid-4 ulose 44. After further manipulations, ( + ) and (—) grandisol (45, 46) are synthesized following Scheme 21. 

Since the alcohol 39 is already known as a precursor for the wrong enantiomer of grandisol, an asymmetric synthesis of the right enantiomer would complete an efficient synthesis. The diene 58 is an ideal substrate for a Sharpless asymmetric epoxidation - reaction occurs only at the allylic alcohol (chapter 25). Two stage conversion of the OH into an iodide and treatment with zinc leads to an elimination 60 and the correct enantiomer of the tertiary alcohol 39 for conversion to grandisol.9... 

The rest of the synthesis is straightforward but you should notice the catalytic Ru(III) oxidation used both on 65 and 67, the periodate cleavage to replace ozonolysis in the formation of 68 and the Peterson reaction (chapter 15) used to make the alkene 69. This method was used for the synthesis of quantities of both enantiomers of grandisol 34. 

Mori, K. Synthesis of the both enantiomers of grandisol, the boll weevil pheromone. Tetrahedron 34,915—920 (1978). 

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