Synthesis of the spiroiminal moiety of marineosins A and B.
A model for the spiroiminal moiety of marineosins A and B was prepared starting from methylvalerolactone. Addition of vinylmagnesium bromide, protection of the alcohol, and reaction of the vinyl ketone with a protected pyrrole-2-carbonitrile N-oxide gave an isoxazoline. Hydrogenolysis of the N-O bond with Raney nickel gave a keto imine that cyclized to a hemi-iminal. O-Methylation, acid-catalyzed cleavage of the TES group and spiroiminal formation, and deprotection completed a seven-step synthesis.
Cai
Xiao-Chuan
XC
Department of Chemistry MS 015, Brandeis University, Waltham, Massachusetts 02454-9110, USA.
Wu
Xiaoxing
X
Snider
Barry B
BB
D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D011758:Pyrroles; D013141:Spiro Compounds; C543079:marineosin A; C543080:marineosin B