Stereoselective Synthesis of Alcohols, XLV:¹Recent Developments in the Generation of the Stereotriad "D"

Total Synthesis of Muamvatin

“…The aldehyde (±)-57 was obtained in 7 steps from methacrolein 56 in a racemic form. 34 Boron mediated aldol reaction of (±)-57 with 3-pentanone (58) …”

Total Synthesis of (−)-Bafilomycin A1: Application of Diastereoselective Crotylboration and Methyl Ketone Aldol Reactions

“…[20] Installation of the difficult anti ± anti stereotriad [21] was accomplished by our diastereoselective aldehyde crotylboration methodology [12] in the mismatched manifold. [22] Thus, the reaction of 9 and (R,R)-diisopropyl tartrate (E)-crotylboronate provided an 85:15 mixture of 10 and the undesired 3,4-anti-4,5-syn diastereomer (78 % yield of 10).…”

Total Synthesis of (−)-Tirandamycin C

“…The highly stereoselective synthesis of this structural motif remains a significant challenge. 6 Many methods involving asymmetric aldol or crotylboration reactions of highly enantioenriched aldehyde substrates fail to provide synthetically useful selectivities for the desired anti, anti -stereotriads. Consequently, multistep, indirect methods have been employed to access this stereotriad unit.…”

“…In general, it is exceedingly difficult to overcome this level of intrinsic aldehyde face selectivity by using a chiral reagent. 6 Subsequent protodestannylation of vinylstannane 18 under acidic conditions (TsOH·H 2 O) 15 gave lactone 7 in 72% yield (over two steps from aldehyde 8 ). The stereochemistry of 7 was assigned as detailed in the Supporting Information.…”