With the correct relative stereochemistry between C1, C2 and C5 set in the Ichikawa-Winstein rearrangement, attempts to install the C6 primary alcohol of 2 were undertaken. Unfortunately, standard allylic oxidation conditions using SeO2 in THF (Scheme 5A) gave only minimal conversion after 24 h and decomposition with extended time. Use of CH2Cl2 gave a similar outcome with full decomposition after 72 h. Although both the alcohol 22a and the aldehyde 22b were detected via mass spectroscopy in trace amounts, the majority of the mass balance was 12. Harsher conditions (stoichiometric SeO2, pyridine in 1,2-DCE, 83 °C) gave only decomposition and urea hydrolysis. We hypothesized the lack of reactivity at C6 might stem from steric crowding by the adjacent C5 stereocenter. The C5 BOM alcohol was deprotected using BF3-Et2O and HSPh to furnish the free alcohol 23 in 96% yield. Treatment with stoichiometric SeO2 under forcing conditions (Scheme 5B) gave only recovered 23. Other allylic functionalizations were also attempted, including visible light and thermal-mediated brominations, both of which gave decomposition. Although the diol 24 possesses the correct C5/C1/C2 functional groups and stereochemical orientation, the C4 oxygen has the wrong stereochemistry and C6 remains unoxidized. From this intermediate, the most direct route involves an elimination of the C4 tertiary alcohol after protection of the C3 secondary alcohol to give 27 (Scheme 7A). Sharpless asymmetric dihydroxylation would install both the C4 and C6 alcohols; the remainder of the synthesis could then be completed using chemistry previously mapped out for the total synthesis of pactamycin. Attempted Burgess elimination of 26 gave complete decomposition. Reaction with 1.2 equiv SOCl2 in the presence of pyridine gave no reaction, but increasing the amount of SOCl2 gave the cyclic sulfite 28, presumably aided by acidmediated BOM deprotection. Conducting the reaction in pyridine gave only decomposition, while the C4 alcohol could not be successfully mesylated and eliminated to furnish 27. Scheme 7. Attempts to install the C4-C6 alkene.