The stereoselective total synthesis of (+)-garvensintriol

Prins cyclization: Synthesis of compounds with tetrahydropyran moiety over heterogeneous catalysts

“…Synthesis of tetrahydropyran type compounds has been previously investigated using different homoallylic alcohols and various aldehydes over a range of acid catalysts [1,2,6,10]. In the current work different parent zeolites as well as their metal modified forms and mesoporous materials were employed in the comparative investigation focused on Prins cyclization of isopulegol and 3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol (diol) with benzaldehyde.…”

“…6 mild reaction conditions [10]. Synthesis of 8-oxabicyclo [3.2.1] oct-2-enes and 9-oxabicyclo [3.3.1] nona-2, 6-dienes from enynol via oxonium /Prins-type cyclization using Au(1) catalyst has been reported by Vandavasi et al [11].…”

“…Preparation of compounds with the desired tetrohydropyran structure can be performed by the acidic catalyzed ene-Prins cyclization of homoallylic alcohol with simple aldehydes [1,2,6]. It is known that Brønsted as well as Lewis acids can catalyze Prins cyclization reactions.…”

An Environmentally Benign Synthesis of Octahydro-2H-chromen-4-ols via Modified Montmorillonite K10 Catalyzed Prins Cyclization Reaction

“…Aldehydes with electron-donating substituents at the para position gave very good yields and excellent diastereoselectivites of the corresponding Prins products (Table 2, entries 3 and 5); whereas o-anisaldehyde afforded an inseparable mixture of products 3d and 4d in a 6.5:1 diastereomeric ratio as determined by 1 HNMR spectroscopic analysis (Table 2, entry 4). Aldehydes with electron-withdrawing groups also underwent cyclization, but their corresponding octahydro-2H-chromen-4-ol derivatives were obtained in lower yields and diastereoselectivities (Table 2, entries [6][7][8][9][10][11][12][13]. Unsubstituted aromatic aldehydes such as benzaldehyde and 2-napthaldehyde also underwent smooth cyclization with the yield of the chromenol derivative for the latter being higher than the former (Table 2, entries 1 and 2).…”

“…Recently, Yadav et al also described an efficient method for the synthesis of octahydro-2H-chromen-4-ol from (R)-citronellal and aldehydes via direct ene-Prins reaction using a catalytic amount of Sc(OTf) 3 under mild conditions (Scheme 2). 7 In the former case the authors only reported one example; whereas in the latter they used Sc(OTf) 3 as catalyst at low temperature. The increasing demand for environmentally friendly and sustainable chemical processes prompted us to develop a novel catalytic system for the Prins cyclization to synthesize a variety of octahydro-2H-chromen-4-ols.…”