Synthesis Golf IV: Plaunotol
16 steps total

Longest linear sequence of 9 steps

Synthesis of Precursor 1:



The hydroformylation of allylamine, Rhodium catalysis (drew the product wrong, it has one more carbon please ignore it for now, I drew the right structure in the one-pot step)
Diazotization of product, occurs immediately before addition to other precursors in one-pot step later on (produces precursor 1)




Synthesis of Precursors 2 &amp; 3



Hydroformylation of methylacrolein, Rhodium catalysis (produces precursor 2)
Protection of aldehyde via hemithioacetal
Protection of ketone through dioxolane
Deprotection of aldehyde by base (produces precursor 3)







Formation of grignard reagent by reaction with magensium of bromoethanal diethyl acetal







One pot reaction, diazo thermolysis resulting in carbene substitution followed by aldol
Weak acid dehydration to form alpha-beta unsaturated ketone
Wittig reaction to establish alkene
Dehydration using Rhenium Catalyst with good selectivity, click here for the paper
Reduction of aldehyde (special reducing agent used just in case free ketone exists)





Deprotection of the ketone (loss of ethane-1,2-diol)
Grignard reaction followed by dehydration to form the ketone of the product
Reduction with lithium aluminum hydride (not shown) to get product, Plaunotol