Ozonolysi tetrahydropyranyl ethers

Hydrolysis of cyclic orthoesters Ozonolysis of tetrahydropyranyl ethers Cleavage of vinyl orthoesters... 

Tufariello and Tegeler18 have described a high-yield synthesis of the quinoliz-idine (11) by cycloaddition of nitrone (9) and the a/3-unsaturated ester (10) and then reduction (Scheme 1). The ester (10) was prepared conveniently from but-3-en-l-ol by ozonolysis of the tetrahydropyranyl ether followed by a Wittig reaction on the resultant aldehyde. The quinolizidine (11) was converted into lupinine (12) by a conventional procedure. 

On angular methylation with protection of the 3o -hydroxy group in the form of the tetrahydropyranyl ether, the furfurylidene derivative (180) formed the trans-C/D and the cis-C/D methyl derivatives (177) and (181), respectively, in a ratio of 1 3.8. Transacetylation, ozonolysis, and esterification of the trans-methyl derivative (177) led to the diester (178), the Dieckmann reaction of which followed by acid hydrolysis gave the hydroxy ketone (179). Oxidation of the 30 -hydroxy group of the latter and the introduction of a A -bond by bromination and dehydrobromination led to the yeast Saccharomyces cerevisiae by a known method [927], a mixture of the c -enantiomer of testosterone (182) and the Z-enantiomer of androstene-dione (183), which were separated chromatographically, was obtained with yields of 70 and 73%, respectively. The over-all yield of Z-testosterone (182) in this synthesis amounted to 2.9% on the (162) (twelve stages) and 1.1% on the unsaturated ketone (140) (16 stages) [921]. 

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