Chiralpak ia column

(S)-3'-carbamoylblebbistatin (S)-16 was synthesized from (S)-3'-cyanoblebbistatin (S)-13
(1.01 g, 3.18 mmol, 1 equiv). Drying of the residue under reduced pressure afforded (S)-16
(0.969 g, 91%) as an ochreous powder. The enantiomeric excess was 86% as determined by chiral HPLC analysis. Portions of 190 mg of the powder were redissolved in 80 mL of boiling absolute ethanol. The cooling solution was left untouched for 24 hours at room temperature, during which time yellow fibers had formed. In one case, evaporation in vacuo of the mother liquor resulted in (S)-3'-carbamoylblebbistatin (S)-16 (0.152 g, 73%) as a yellow powder with an enantiomeric excess of 98%. In one other case, the crop afforded (S)-3'-carbamoylblebbistatin (S)-16 (0.0422 g, 20%) as bright yellow fibers with an enantiomeric excess of 98%. The three other recrystallizations resulted in scalemic mixtures in both the crops and the mother liquors. In those cases the crop and the mother liquor were recombined and the recrystallization protocol was repeated. mp 267 °C. Chiral HPLC: t R ((S)-16) = 20.9 min, t R ((R)-16) = 17.6 min (Daicel Chiralpak IA column, hexane/dichloromethane/absolute ethanol (10:90:3), 0.5 mL min -1 , 35 °C).
[α] 25 D = -288 ± 5 (c = 0.07 in tetrahydrofuran). 1

The asymmetric α-hydroxylation of quinolones 9a,b,d was adopted from Lucas-Lopez et al. 20 An oven-dried bulb of 50 mL, evacuated and back-filled with argon (5×), was loaded with 5 mL of dry tetrahydrofuran and quinolone (1.00 mmol, 1 equiv). Then, the solution was cooled The combined organic extracts were dried over magnesium sulfate and evaporated in vacuo. 20 (S)-blebbistatin (S)-1 was synthesized from quinolone 9a (0.276 g, 1.00 mmol, 1 equiv) using Davis' oxaziridine 14 (0.716 g, 2.40 mmol, 2.4 equiv). Evaporation in vacuo gave (S)-1 (0.250 g, 85%) as bright yellow powder. The enantiomeric excess was 75% as determined by chiral HPLC analysis. This powder was redissolved in 10 mL of boiling acetonitrile and left untouched overnight at room temperature, which afforded (S)-blebbistatin (S)-1 (0.108 g, 37%) as bright yellow crystals with an enantiomeric excess of >99%. Chiral HPLC: t R ((S)-1) = 7.32 min, t R ((R)-1) = 9.77 min (Daicel Chiralpak IA column, acetonitrile/water (50:50), 1.0 mL min -1 ,

Dichloromethane was dried by heating under reflux over CaH 2 and distilled under an atmosphere of nitrogen. Tetrahydrofuran was dried by heating under reflux with sodium/benzophenone under a nitrogen atmosphere and collected by distillation. Dry 1,4-dioxane and dry methanol were purchased from Sigma-Aldrich and Acros Organics, respectively. Reagents were purchased at the highest commercial quality and were used as received without further purification.
Yields refer to chromatographically and spectroscopically ( 1 H NMR) homogeneous material, unless otherwise stated.
Reactions were monitored on an Agilent 1200 series HPLC system fitted with an Ascentis® Express C18-column (2.7 µm particle size, 4.6 mm internal diameter), using acetonitrile/water The enantiomeric excess (ee) of chiral compounds was determined via chiral HPLC analysis using a Daicel Chiralpak IA column (5 µm particle size, 150 mm length, 2.1 mm internal diameter). Detection wavelengths were set at 268, 234 and 296 nm. Analyses under reversed phase and normal phase conditions were performed at 25 °C and 35 °C, respectively. Optical rotations were obtained on a Jasco P-2000 polarimeter and are reported in deg mL g -1 dm -1 ; concentrations are reported in grams per 100 mL.