What feature of the citronellol structure shows that it is unsaturated
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Answer:
Similar to citronellol, the chiral pool applications of citronellal are characterized by the utilization of the differentiable end groups in various ring-forming operations.
So, it is no big surprise that II has been used for IMDA reactions, for instance, in the synthesis of the fungal metabolite hirsutellone B (Scheme 5).7 Thus, (R)-citronellal II was converted into epoxy vinyl iodide 5.2 which was used in a Stille cross coupling with stannane 5.3 to give polyene 5.4. Under the influence of Et2AlCl, the stannane undergoes a Sakurai-type cyclization with the epoxide to generate cyclohexane derivative 5.5 to which two additional rings are annulated in a tandem IMDA reaction. The tricyclic intermediate 5.6 was thus obtained stereoselectively. The next subgoal was the conversion of 5.6 into sulfone 5.10. Mukaiyama etherification and reduction of the ester led to aldehyde 5.7 which was used for the extension of the sidechain to deliver ketone 5.8 after functionalization of the aryl methyl group. Introduction of a thioaetate- and a primary iodide led to intermediate 5.9 which was cyclized to the thioether under basic conditions. Oxidation furnished sulfone 5.10. Ramberg–Bäcklund ring contraction led to (Z)-cycloolefin which was carboxylated to the β-keto ester. Sharpless asymmetric dihydroxylation (AD) of the olefin and regioselective Barton–McCombie deoxygenation of the diol afforded alcohol 5.11 stereoselectively. Oxidation of the alcohol to the ketone was followed by heating with NH3 to obtain 5.12 via an amidation – C-17 – epimerization cyclization cascade.
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Similar to citronellol, the chiral pool applications of citronellal are characterized ... The construction of the strained trans-fused ring of englerin was achieved via ... Inversion of the OH-function and hydrogenation furnished diol 6.7, whose more ... observed are citronellal, citronellol, unsaturated alcohols (geraniol and nerol).
Explanation: