SYNTHESIS OF OPTICALLY-ACTIVE CIS- AND TRANS-1,2-DISUBSTITUTED CYCLOPROPANE DERIVATIVES BY THE SIMMONS-SMITH REACTION OF ALLYL ALCOHOL DERIVATIVES DERIVED FROM (R)-2,3-O-ISOPROPYLIDENEGLYCERALDEHYDE
T. Morikawa et al., SYNTHESIS OF OPTICALLY-ACTIVE CIS- AND TRANS-1,2-DISUBSTITUTED CYCLOPROPANE DERIVATIVES BY THE SIMMONS-SMITH REACTION OF ALLYL ALCOHOL DERIVATIVES DERIVED FROM (R)-2,3-O-ISOPROPYLIDENEGLYCERALDEHYDE, Journal of organic chemistry, 59(1), 1994, pp. 97-103
The Simmons-Smith reactions of Z- and E-allyl alcohol derivatives 6 de
rived from (R)-2,3-O-isopropylideneglyceraldehyde (5) were used for th
e synthesis of optically active cis- and trans-1,2 disubstituted cyclo
propane derivatives. Reaction of 6 with diethyl zinc and diiodomethane
gave cyclopropane derivatives 7 in 84% to quantitative yields with 35
to approximate to 100% des. Identical facial selectivities toward the
double bonds, Ire-asi for Z-6 and 1re-2re for E-6, were observed in t
he cyclopropanations. The diastereoselectivity was dependent on the pr
otecting group on the terminal allylic oxygen (R of 6, TBDPS > MOM > B
n) and on the stereochemistry of the double bond (Z > E). For TBDPS et
hers Z- and E-6c, cis- and trans-7c were obtained as single diastereom
ers respectively. It was clearly demonstrated that the stereoselectivi
ty of the cyclopropanation is controlled by the directing effect of th
e allylic oxygen (O-1) of the dioxolane ring which coordinates to the
reagent. The terminal allylic oxygen (O-2) lowered the diastereoselect
ivity This reaction was applied to the synthesis of optically active c
yclopropane analogs of gamma-aminobutyric acid (GABA) 18, 22, and ent-
22.