Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• underwent Prins-type cyclization in the presence of BF3·OEt2 as well as SnBr4 to deliver the desired 37 and 40, respectively, without loss of optical purity (Scheme 9) [34][35]. This strategy was successfully utilized for the synthesis of the natural product (−)-centrolobine [33] and for the stereoselective

• -trisubstituted tetrahydropyran 97 through Prins cyclization, as shown in Scheme 21. Similarly, an SnCl4-catalyzed Prins reaction was reported for the synthesis of 4-chlorotetrahydropyran 100. This intermediate was further utilized for the synthesis of the natural product centrolobine, as shown in Scheme 22 [56

• and homoallylic alcohol 110 using TMSCl and NaI. Furthermore, the major diastereomer was utilized for the synthesis of centrolobine, as shown in Scheme 26 [60]. Loh and co-workers have shown the construction of cis-2,6-disubstituted tetrahydropyran 116 with an exocyclic double bond by reacting

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• reactions with Grubbs catalyst and terminal alkenes. However, the corresponding mono- or diallyl vinylphosphonate esters undergo facile cross metathesis reactions. The improved reactivity is attributed to a relay step in the cross metathesis reaction mechanism. Keywords: centrolobine; metathesis; organo

• synthesis of centrolobine (8) [9], an antileishmananial compound isolated from the heartwood of various Centrolobium species [12][13][14][15][16] (Scheme 2). The cis-THP substituted vinylphosphonate 5, formed by a stereospecific palladium-catalyzed cyclization of phosphono allylic carbonate 4, was cleaved

• via ozonolysis to the aldehyde 6, a known intermediate [17][18] on route to (−)-centrolobine (8). An alternative approach could involve an alkene cross metathesis reaction between the vinylphosphonate and a styrene (5 to 7). Since substituted vinylphosphonates are reluctant to participate in cross

Efficient, highly diastereoselective MS 4 Å-promoted one-pot, three-component synthesis of 2,6-disubstituted-4-tosyloxytetrahydropyrans via Prins cyclization

• Naseem Ahmed and
• Naveen Kumar Konduru

Beilstein J. Org. Chem. 2012, 8, 177–185, doi:10.3762/bjoc.8.19

• phorboxazoles (A and B) [1], (−)-centrolobine [2], GEX1A/herboxidiene [3], bryostatins [4], and pheromones [5] (Figure 1). Tetrahydropyran derivatives are also used as materials in photographic films [6] and host–guest chemistry [7]. In particular, 2,4,6-trisubstituted tetrahydropyrans have tremendous