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, DFT computations did not suggest coordination of the O atom of the methylenealkoxy moiety onto the active yttrium center to be a favored process, although it cannot be completely ruled out at this stage (see ref [11] and [112]). The interference on stereocontrol of heteroatom(s) in functional side-arms of ?-lactones is currently under investigation in our laboratory

, Note that in our initial communication (ref [11]), we inadvertedly inverted the assignments of main-chain (backbone) and lateral (functional) methylene resonances

, 11 in Figure 4) are found at ? ca. 36 ppm while carbons of the lateral methylene (e.g. C 6,13 and also C 7 in Figure 4) are found at ? ca. 70-72 ppm, Main-chain methylene carbons, vol.4