Triphenylphosphine–iodine: an efficient reagent for the regioselective dehydration of tertiary alcohols

First synthesis of antitumoral dasyscyphin B

“…The mixture was concentrated in vacuo to give a crude product, which was diluted with ether-water (50-20 mL) and the phases were shaken and separated. The organic phase was washed with water and brine and dried over anhydrous ( (14). 12 To a solution of 11 (1.00 g, 2.87 mmol) in THF (20 mL) was added a 50% aqueous solution of RANEY® Nickel (4 mL), and the mixture was stirred at room temperature for 2 days, at which time TLC showed no 11.…”

Total Synthesis of (−)‐Melotenine A

“…The endgame in the asymmetric synthesis of (−)‐melotenine A required regioselective dehydration of the tertiary, allylic C19 carbinol. To this end, we screened a variety of reaction conditions and ultimately found success in the Appel protocol (i.e., PPh 3 , I 2 ), which furnished (−)‐ 1 in 44 % yield 18. Spectroscopic data for synthetic (−)‐melotenine A (e.g., 1 H and 13 C NMR spectroscopy, and IR) were in complete agreement with those reported for natural (−)‐ 1 by Luo and co‐workers 2.…”

Ilicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive α‐ and β‐Eudesmol

“…POCl 3 /pyridine [19] -20 86 2 2 -POCl 3 /pyridine [19] 100 57 17 16 -I 2 /Ph 3 P [20] r.t. 10 -85 -I 2 /Ph 3 P [20] [24] with the use of diethyl -(-)-tartrate as chiral auxiliary led to a 6:1 mixture of 11 and 12 as shown by 1 H NMR spectroscopy. Subsequent reduction of this mixture with LiEt 3 BH yielded 4 with a diastereomer excess of 70 %.…”