Stereoselectivity of electrophile-promoted oxacyclizations of 1,4-dihydroxy-5-alkenes to 3-hydroxytetrahydropyrans

McDonald, Frank E.; Ishida, Kento; Hurtak, Jessica A.

doi:10.1016/j.tet.2013.04.138

Cited by 12 publications

(13 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly when 1.4-dihydroxy-5-alkyne derivatives were subjected to a Hg(OTf) 2 -catalyzed cyclization then oxacyclization takes place to form tetrahydropyran derivatives ( Scheme 43 ) [ 101 ]. Later it was shown that alkynyl diol 150 when treated with 20 mol % Hg(OTf) 2 followed by Et 3 SiH afforded bispyranoyl ketone 151 , but when Hg(OTf) 2 was increased (1 equiv) then fused pyran-oxocane derivative 152 was isolated [ 102 ].…”

Section: Reviewmentioning

confidence: 99%

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

Mandal¹,

Chaudhari²,

Biswas³

2021

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

The synthesis of complex cyclic compounds is extremely challenging for organic chemists. Many transition-metal-salt-mediated cyclizations are reported in literature. Hg(II) salts have been successfully employed in cyclizations to form complex heterocyclic and carbocyclic structures that are impossible to synthesize with other transition metal salts. In this review, we have summarized cyclization reactions that are performed with Hg(II) salts. These salts are also successfully applied in stoichiometric or catalytic amounts to form complex cyclic structures and natural products.

show abstract

Section: Reviewmentioning

confidence: 99%

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

Mandal¹,

Chaudhari²,

Biswas³

2021

Beilstein J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…than the established Hg(II)-catalyzed alkynyl alcohol cycloisomerization (Scheme 5, step 1), 4 with formation of hemiacetal 15 from addition of adventitious water to enol ether 14. The desired 7-exo-mode cycloisomerization with the remaining alkyne must be slower than the acid-catalyzed dehydrative cyclization displacing the secondary propargylic alcohol (Scheme 5, step 2), affording bispyranyl alkyne intermediate 16.…”

Section: Letter Syn Lettmentioning

confidence: 99%

“…In conclusion, attempts to extend oxacyclizations of alkynyl alcohols with substrates 6, 25, and 26 have paralleled some of our experiences with alkenyl alcohols: dehydrative oxacyclization processes have occurred with some simple alkenyl alcohol substrates under acidic conditions. 4 Moreover, substrates designed to undergo 7-exo-mode oxacyclization have instead favored formation of eight-membered rings, to the exclusion of seven-membered ring isomers. 26,27 However, the insights gained in these studies have provided the background for successful sequential exo-mode cyclizations of polyene-polyols, in work that will be described separately.…”

Section: Syn Lettmentioning

confidence: 99%

“…The mercuric triflate-catalyzed tandem cyclization of (S,S)-6 using the same conditions as described earlier 4 gave numerous products, with the bispyranyl ketone 13 isolated as the major product in 22% yield as a 5.7:1 mixture of diastereomers (Scheme 4). 13,14 In addition to considerable spectroscopic evidence for structure 13, the product did not undergo acylation, consistent with the absence of a secondary alcohol.…”

mentioning

confidence: 94%

“…In 2013, we reported regio-and diastereoselective electrophile-promoted oxacyclization reactions of alkenyl diol substrates, furnishing 3-hydroxytetrahydropyrans. 4 Particularly notable was the superior trans-selectivity observed from oxacyclization of cis-disubstituted alkene 2 with stoi-chiometric mercuric trifluoroacetate, followed by demercuration to provide tetrahydropyran 3 (Scheme 1). Although the results were promising, the requirement of stoichiometric toxic Hg(II) and tributyltin hydride was a significant limitation of the alkenyl diol cyclization process.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Regioselectivity of Mercury-Promoted Oxacyclizations of Alkynyl Diols

Hurtak

McDonald

2017

Synlett

View full text Add to dashboard Cite

Supporting InformationS-3 II. Synthesis of diynyl triol (S,S)-6Preparation of (±)-8: HgCl 2 (90 mg; 0.33 mmol) and Mg 0 (3.65 g; 150 mmol) were added to a two-neck oven-dried 250 mL round bottom flask equipped with reflux condenser. A solution of propargyl bromide (0.4 mL) in Et 2 O (16 mL) was added. The resulting suspension was heated gently with a heating gun to initiate the reaction, resulting in bubbling which persisted after heating ceased. The flask was then cooled to 0 °C, before dropwise addition of the remaining propargyl bromide (5.2 mL; 50 mmol total) in Et 2 O (30 mL) over 20 min. The reaction continued to bubble upon and after addition of propargyl bromide. After stirring at 0 °C for 15 min, the grey Grignard solution was transferred via cannula to a flask containing propargyl aldehyde 7 2 (2.38 g; 12.6 mmol) in THF (62 mL) at -78 °C. The reaction was stirred at -78 °C for 3 h, after which time it was quenched by addition of sat'd aq. NH 4 Cl (20 mL) and allowed to warm to room temperature. The organic layer was separated and the aqueous layer was extracted with Et 2 O (3 x 20 mL). The combined organic extracts were washed with brine, dried over Na 2 SO 4 , filtered, and concentrated under reduced pressure to afford the crude product as a yellow oil, which was purified by silica gel flash column chromatography (20% EtOAc in hexanes) to afford racemic diynyl alcohol 8 as a clear, colorless oil (2.44 g; 10.7 mmol; 85% yield). O OBn H 7 R + OR OBn H H S Supporting Information S-4 1 H NMR for diynyl alcohol (±)-8: (600 MHz, CDCl 3 ) δ 7.39 -7.29 (m, 5H), 4.56 (s, 2H), 4.52 (dtd, J = 8.0, 5.9, 1.9 Hz, 1H), 3.60 (t, J = 7.0 Hz, 2H), 2.61 (m, 2H), 2.56 (td, J = 7.0, 1.9 Hz, 2H), 2.20 (d, J = 6.3 Hz, 1H), 2.11 (t, J = 2.6 Hz, 1H).Resolution of (±)-8 to prepare diynyl ester (R)-8 and diynyl alcohol (S)-9: Powdered 3Å molecular sieves (1.5 g) and Pseudomonas AK (1.12 g) were added to a solution of racemic diynyl alcohol 8 (2.24 g; 9.80 mmol) in hexanes (100 mL). Vinyl acetate (4.0 mL) was then added. The suspension was stirred and monitored for conversion by 1 H NMR spectroscopy.After 4 h, the reaction had reached 50% conversion by 1 H NMR. The reaction mixture was filtered through Celite, rinsed with CH 2 Cl 2 , and concentrated under reduced pressure to afford a pale-yellow oil. The crude reaction mixture was purified by silica gel flash column chromatography (18% EtOAc in hexanes) to afford diynyl ester (R)-9 (1.10 g; 4.07 mmol; 42% yield) and diynyl alcohol (S)-8 (854 mg; 3.74 mmol; 38% recovery; 80% combined yield of 8 and 9). MTPA-esters confirmed the stereochemical assignment and purity of (S)-8 (er > 95:5; the other stereoisomer was not visible). Data for diynyl ester (R)-9: [α] D 25 +48.8 (c=1.0, CHCl 3 ) 1 H NMR (600 MHz, CDCl 3 ) δ 7.39 -7.30 (m, 5H), 5.50 (app. tt, J = 6.3, 2.0 Hz, 1H), 4.56 (s, 2H), 3.60 (t, J = 7.1 Hz, 2H), 2.67 (dd, J = 6.2, 2.6 Hz, 2H), 2.56 (td, J = 7.1, 2.0 Hz, 2H), 2.11 (s, 3H), 2.05 (t, J = 2.7 Hz, 1H).OH OBn

show abstract

Addition Reactions: Polar Addition

Kočovský¹

2016

Organic Reaction Mechanisms · 2013

View full text Add to dashboard Cite

Stereoselectivity of electrophile-promoted oxacyclizations of 1,4-dihydroxy-5-alkenes to 3-hydroxytetrahydropyrans

Cited by 12 publications

References 48 publications

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

Regioselectivity of Mercury-Promoted Oxacyclizations of Alkynyl Diols

Addition Reactions: Polar Addition

Contact Info

Product

Resources

About