A highly stereocontrolled synthesis of α-hydroxycyclopropanes possessing a trifluoromethyl group

Stereoselective Cyclopropanation Reactions

“…The selectivities obtained in the cyclopropanation of other simple ( E )-disubstituted chiral allylic alcohols with these various reagents are shown in Table . The general trends described above are maintained with more complex systems.…”

“…For example, the substitution of a methyl group (Table , entry 12) by a trifluoromethyl group (Table , entry 19) with the samarium reagent led to a spectacular increase of the syn selectivity. Lautens and Delanghe have shown that this reaction can be extended to silyl-substituted olefins (Table , entries 21−26). 48e,f …”

Application of lanthanide reagents in organic synthesis

“…In an elegant approach to polyquinenes, Cook and Lannoye developed a bis-annulation process based upon the Sml2-mediated cyclization process (eq 208).142 2Sml2 THF, HMPA 68% (208) Remarkably, each of the carbon-carbon bond forming reactions in this process proceeds in over 80% yield, and in other analogous substrates they exceed 90%, providing an efficient entry to complex molecules.…”

Stereospecific and highly stereoselective cyclopropanation reactions promoted by samarium

“…6b Molander's methodology 6 has been employed in the preparation of optically pure syn-a-hydroxycyclopropanes possessing a trifluoromethyl group (Scheme 7). 13 The authors observed that (S or R)-(E) and (S or R)-(Z)allylic alcohols could be easily cyclopropanated giving only the syn-stereoisomer via the Houk model. So, in all cases studied, the corresponding syn-a-hydroxycyclopropanes were obtained in high yields and stereoselectively.…”