Iodine as a versatile reagent for the Prins-cyclization: an expeditious synthesis of 4-iodotetrahydropyran derivatives

Mild and Phosphine-Free Iron-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides with Alkynyl Grignard Reagents

“…The crude product was purified by flash chromatography with silica gel using hexanes as an eluent to afford (2-iodopropyl)benzene (S7) as colorless oil (15.7 4-Iodo-2-phenyltetrahydro-2H-pyran (S8). [18] Following the general procedure B, the title compound was prepared using benaldehyde (4.24 g, 40 mmol), 3-buten-1-ol (5.77 g, 80 mmol), and iodine (10.2 g, 40 mmol). The crude product was purified by flash chromatography with silica gel using hexanes/EtOAc (15:1) as an eluent to afford 4-iodo-2-phenyltetrahydro-2H-pyran (S8) as brown oil (6.33 g, 22.0 mmol, 55%).…”

On the choice of Lewis acids for the Prins reaction; two total syntheses of (±)-Civet

“…27 More interestingly, there are a few examples of oxygenated nucleophiles incorporated, including OAc from BF 3 $OEt 2 /AcOH/TMSOAc; 28 OH indirectly from TFA. 29 External nucleophiles have also been incorporated into tetrahydropyrans by adding additives to the reaction, such as sulfur-centred nucleophiles introducing thioaryl groups; 30 nitrogen-centred nucleophiles, including acetonitrile in PrinseRitter 31e34 sequences and azides; 35 carbon nucleophiles such as tandem PrinseFriedeleCrafts reactions.…”

“…Prepared according to general procedure using phenylacetaldhyde (292.7 ml, 2.5 mmol), trimethylsilyl trifluoromethanesulfonate (603.8 mg, 3.3 mmol), 2-fluorobut-3-en-1-ol (150 mg, 1.7 mmol) and dry CH 2 Cl 2(15 ml) to afford the title compound as a pale yellow oil (182.3 mg, 0.5 mmol, 32%); R f 0 27. (5% EtOAc in petrol); found [M] þ 342.0553; C 13 H 14 F 4 O 4 S requires 342.0549; n max /cm À1 (thin film) 3058 (m, aryl CeH), 2983-2846 (m, CeH), 1602, 1493 (w, aryl CeH), 1419 (s, eSO 2 eOe), 1266 (s, CeF), 1218, 1144 (s, eSO 2 eOe); d H (400 MHz, CDCl 3 ) 7.34 (2H, m, aryl CH)1F, m, CHF); m/z (EI) 343 [(MH) þ , 15%], 252 [(MH) þ , eCH 2 Ph, 35%], 193 [(MH) þ , eOTf, 26%].…”

Gallium(III) Iodide Mediated Mild and Efficient Method for Synthesis of 4-Iodotetrahydropyrans by Cross-Cyclization of Epoxides and Homoallylic Alcohols

“…Zurwerra et al [5] reported the synthesis of (-)-dactylolide from 4-iodotetrahydropyran derivative. Even though there is considerable demand for 4-iodotetrahydropyrans, limited methods are available in the literature [6][7][8][9][10][11]. Among the existing methods, Prins cyclization is the common and widely used method for the tetrahydropyrans synthesis.…”