MPM (4-methoxybenzyl) protection of hydroxy functions under mild acidic conditions

Synthetic studies related to the akuammiline alkaloids

“…Despite seemingly excellent precedents in which an analogous 5,6-ring system was constructed, 33 the best that could be claimed in our experiments were signals in 1 H NMR spectra, of complex product mixtures, which could have represented some of the desired product. We explored the possibility of achieving the desired benzylic electrophilic reactivity by decomposition of a trichloroacetimidate; 34,35 the required derivative 9c was easily prepared following a literature precedent, 36 but various attempts to effect the desired acid-catalysed closure were unsuccessful (Scheme 2). …”

p-Nitrobenzyl Trichloroacetimidate

“…356-358K), and the structure was therefore determined crystallographically in order to ascertain the geometry of the imidate group. Other benzyl trichloroacetimidates have been prepared, notably the parent compound (Wessel, Iversen & Bundle, 1985) and also p-methoxybenzyl trichloroacetimidate (Nakajima, Horita, Abe & Yonemitsu, 1988).…”

Synthesis of the Southern FGHI Ring System of Azaspiracid‐1 and Investigation into the Controlling Elements of C28‐ and C36‐Ketalization

“…On the basis of this setback, we chose to revise our approach (Scheme 5). Starting from the known PMB-protected ester 28, [11] DIBAL-H reduction, iodination, and Myers alkylation gave 30. Conversion of 30 into the methyl ketone followed by DDQ deprotection and two-step azide incorporation gave 32.…”