Finally, cyclization to introduce the second morpholine ring, afforded 5-and 6-methyl-substituted spiroacetals, 46 and 47, respectively, in good yields. In both cases, the diastereoisomeric ratio of the iodoacetal starting materials was preserved in the spiroacetal products, suggesting efforts to improve the diastereomeric ratio, for example using a chiral electrophilic iodine reagent would be worth exploring in the future (Scheme 8). It was not possible to determine by NMR spectroscopy the orientation of the methyl substituent in the two diastereoisomers of spiroacetal 46 (5-Me) owing to resonance overlap and the presence of rotamers; however, the appearance of the resonance for one of the C(5)Hs in the major diastereoisomer of spiroacetal 47 (6-Me) as an apparent triplet [H = 1.81 (app t, J = 10.9 Hz)] is consistent with an axially oriented hydrogen substituent at C( ) (Scheme 8). We were unable to confirm the stereochemistry of the spiroacetal; however, given literature precedent, we hypothesize that this diastereisomer is the double anomerically stabilized spiroacetal with an equatorial methyl substituent. Incorporating substituents into the ring formed in the final cyclization step proved more straightforward. Ten commercially available, enantiopure (where applicable) Boc-protected aminoalcohols were used to produce substituted spiroacetals 48-58 (Figure ). In most cases, the spiroacetals were isolated in greater than 60% yield from enol ether 2f and where relevant, as 1:1 mixtures of diastereoisomers, highlighting the stereochemical information embedded in the nucleophile imparted no stereoinduction. The formation of 1,1-dimethyl-2-isopropyl-substituted spiroacetal 55 was low-yielding, presumably because of the sterically hindered tertiary alcohol employed in the iodoacetalization step. The reaction sequence to form benzene-fused spiroacetal 57 was also low-yielding, which we propose is a consequence of the lower nucleophilicity of both the phenol in the iodoacetalization step and the aniline carbamate in the cyclization.