Regio- and stereocontrolled synthesis of epoxy alcohols and triols from allylic and homoallylic alcohols via iodocarbonates

A simple stereoselective synthesis of (+)-[6]-gingerdiol

“…The later was treated with di (tert-butyl) carbonate in the presence of DMAP to form the homoallylic tert-butyl carbonate, 9. The treatment of compound 9 with I2 in MeCN at -20 O C furnished the iodocarbonate 10 which was subsequently treated with K2CO3 in MeOH to afford the synepoxy alcohol 11 The cleavage of the TBS ether group also took place simultaneously [14,15]. Finally, the reaction of compound 11 with Grignard reagent, n-C4H9MgBr using CuI produced the target molecule, (+)- [6]-gingerdiol (1) [16].…”

A Simple and Efficient Approach to 1,3‐Polyols: Application to the Synthesis of Cryptocarya Diacetate

“…To improve the diastereoselectivity of this reaction, we applied a threestep sequence based on a modified Cardillo iodo cyclization procedure. [12] Following this methodology, the homoallylic tert-butyl carbonate 16 was prepared from the corresponding alcohol 15 in 90 % yield by treatment with di-tert-butyl dicarbonate in the presence of DMAP (DMAP = 4-dimethylaminopyridine) in acetonitrile. The diastereoselective iodineinduced electrophilic cyclization of the homoallylic tert-butyl carbonate 16 with IBr at low temperature (À85 8C) furnished the iodo carbonate 17, which was directly treated with K 2 CO 3 in methanol to give the desired syn-epoxy alcohol 18 as a single diastereomer in 81 % yield.…”

“…[9] As a part of our research program, aimed at developing enantioselective syntheses of naturally occurring lactones, [10] we became interested in devising a practical and concise route to syn-1,3-polyols/5,6-dihydropyran-2-ones. Herein we report our successful endeavors towards the development of a general and practical route for 1,3-polyols and its subsequent application to the stereoselective total synthesis of cryptocarya diacetate (2), employing hydrolytic kinetic resolution (HKR), [11] diastereoselective iodine-induced electrophilic cyclization, [12] and ring-closing metathesis (RCM) [13] as the key steps. The HKR method utilizes the readily accessible cobalt-based chiral salen complex 5 as a catalyst (Figure 2) and water to resolve a racemic epoxide into an enantiomerically enriched epoxide and diol in high enantiomeric excess.…”

Synthesis of aminothiazoles: polymer-supported approaches

“…Herein, two polymeric bases were found to be effective: MP-carbonate (macroporous triethylammonium methyl polystyrene carbonate resin) 101, a resin-bound equivalent of potassium carbonate (K 2 CO 3 ), [73][74][75] and PS-DIEA (N,N-(diisopropyl)aminomethyl-polystyrene) resin 102.…”