Direct Regioselective [3 + 2]-Cyclization Reactions of Ambivalent Electrophilic/Nucleophilic β-Chlorovinyl Dithianes: Access to Cyclopentene Derivatives

Abstract

The highly regioselective and operationally straightforward [3 + 2] cyclizations of β-chlorovinyl dithianes with α,β-unsaturated carbonyl compounds have been developed. This protocol provides direct access to highly functionalized cyclopentenes with perfect chemo- and regioselectivities under extremely mild reaction conditions. In particular, the unprecedented cyclization allows for the selective preparation of hydroxylated cyclopentenes.

Enantioselective α-Functionalization of 1,3-Dithianes by Iridium-Catalyzed Allylic Substitution

“…Petroleum ether/ethyl acetate (20:1) as the eluent; colorless oil (starting from 5 mmol of 2-carboxy-1,3-dithiane, 1.05 g, 96%); 1 H NMR (400 MHz, CDCl 3 ) δ 5.85 (dqt, J = 15.5, 6.5, 1.2 Hz, 1H), 5.62 (dtq,J = 14.9,6.6,1.7 Hz,1H),4.60 (dp,J = 6.6,1.1 Hz,2H),4.18 (s,1H),3.42 (ddd,J = 14.2,11.5,2.7 Hz,2H),2H),2H), 1.74 (dq, J = 6.6, 1.2 Hz, 3H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ 169. 5,132.0,124.4,66.2,39.9,25.9,25.0,17.8;HRMS (ESI) Compound 4f. Petroleum ether/ethyl acetate (20:1) as the eluent; colorless oil (starting from 5 mmol of 2-carboxy-1,3-dithiane, 1.37 g, 92%); 1 H NMR (400 MHz, CDCl 3 ) δ 7.38 2H),2H),6.67 (d,J = 15.8 Hz,1H),6.22 (dt,J = 15.9,6.4 Hz,1H),4.82 (d,J = 6.3 Hz,2H),4.22 (s,1H),1H),1H),1H); 13 C { 1 H} NMR (100 MHz, CDCl 3 ) δ 169.…”

“…13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ 169. 5,141.0,127.9,127.4,126.7,125.1,121.8,65.8,39.9,25.9,25.0;HRMS (ESI) m/z: [M + Na] + calcd. for C 12 H 14 NaO 2 S 3 , 309.0048; found, 309.0056.…”

“…3 Therefore, 1,3-dithianes are found to be versatile building blocks for the formation of many important organic compounds and natural products. 4,5 However, the catalytic enantioselective addition reactions of 1,3-dithianes are still largely unexplored due to their incompatibility with other catalytic reaction systems. So far, only a few papers reported the enantioselective addition reaction of 1,3-dithianes with different electrophiles in a catalytic manner.…”