You have been warned (previous post here), this is platencin total synthesis number 10 (Varseev & Maier 2009 DOI).

Starting material is 3-isobutoxycyclohex-2-en-1-one 1, formylation with isobutyl formate 2 is followed by nucleophilic substitution to allyl chloroformate 3 forming an E/Z mixture of allyl carbonate 4. A Carroll rearrangement introduces the quaternary carbon atom in 5 (step also performed as an asymmetric synthesis), an hydride reduction to alcohol 6 is followed by protective group addition to pivaloyl ester 7. Conversion to silyl enol ether 8 is followed by cyclization (oxygen, palladium acetate) to exocyclic alkene 9. Addition of Ketene silyl acetal 10 forming 11 is a Mukaiyama-Michael Addition.

The ketone 11 is converted to hydrazone 12. This compound reacts with NaCNBH₃ and ZnCl₂ to free radical intermediate 13 which rearranges the 3.2.1 platensimycin core to the 2.2.2 platencin core in 14. Conversion of the ester group in 14 to a ketone takes place through Weinreb amide 15 and MeLi , the intermediate 16 is a hemiacetal. The final steps are reduction (LiAlH₄) to diol 17, Swern oxidation to aldehyde 18 and a ring-closing aldol condensation to the platencin core 19.