Asymmetric synthesis of (+)-passifloricin A and its 6-epimer

Retracted Article: Organocatalytic stereoselective synthesis of passifloricin A

“…(S)-Ethyl 4-(tert-butyldimethylsilyloxy)octadecanoate (8) To a solution of palmitaldehyde 6 (2.0 g, 8.3 mmol) and nitroso benzene (0.89 g, 8.3 mmol) in anhydrous CH 2 Cl 2 (29 mL) was added D-proline (0.38 g, 3.2 mmol) at 20 °C. The mixture was vigorously stirred for 25 min under argon (the color of the reaction changed from green to yellow during this time), then cooled to 0 °C.…”

“…IR (neat, cm −1 ): ν max 3412, 3018, 2938, 1612, 0.89-0.85 (m, 3H); 13 C NMR (50 MHz, CDCl 3 ): 98. 8,71.9,71.5,71.4,69.4,69.3,66.5,39.3,37.6,37.4,37.1,37.0,33.5,33.1,33.0,32.2,31.9,30.1,29.7,25.7,22.7,19.9,19.7,14.1;HRMS (ESI) To a mixture of diol 17 (0.26 g, 0.04 mmol), in dry CH 2 Cl 2 (5 mL) dibutyltin oxide (catalytic) was added followed by the addition of p-toluenesulfonyl chloride (0.008 g, 0.04 mmol) and triethylamine (0.006 mL, 0.04 mmol) and reaction was stirred at room temperature under nitrogen. The reaction was monitored by TLC, after completion of reaction the mixture was quenched by adding water.…”

“…1). Subsequently Chandrasekhar et al 8 accomplished the total synthesis of 1 using Jacobsen epoxidation and Evans intramolecular oxa-Michael reaction 9 as key transformations, while Sabitha et al 10 described its synthesis by employing Prins cyclization as the key step.…”

Recent Advances in the Stereoselective Total Synthesis of Natural Pyranones Having Long Side Chains

“…In recent years, several new syntheses of passifloricin (161b) have been reported. Chandrasekar et al prepared the compound starting from the olefin (162) (Scheme 33) [98]. This was converted to the chiral epoxide 163 by epoxidation followed by resolution of the racemic form using Jacobson's catalyst.…”

Convergent Synthesis of Passifloricin A via a Prins Cyclisation and Olefin Cross-Metathesis Approach

“…Later on, a linear synthesis of 1 appeared. 8 We were attracted to passifloricin A (1) because of its interesting structure and important biological activities. The Prins cyclisation has emerged as a powerful synthetic tool for the construction of substituted tetrahydropyran rings of natural products.…”