Preparation of eight-membered cyclic ethers by Lewis acid promoted acetal-alkene cyclizations

Blumenkopf, Todd A.; Bratz, Matthias; Castañeda, Armando; Look, Gary C.; Overman, Larry E.; Rodriguez, D.; Thompson, Andrew S.

doi:10.1021/ja00167a041

Cited by 96 publications

(20 citation statements)

References 2 publications

(3 reference statements)

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“…For instance, treatment of acetal 124 with SnCl 4 unveiled eight-membered cyclic ether 125, which still contains a vinylsilane function. [73] This product may arise via an ene pathway in which the two R groups are arranged according to the conformational preferences of the (Z)-cyclooctene-type scaffold [Eq. (17)].…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Long¹,

Aye

2009

Chemistry A European J

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An up-to-date in-depth review of the current virtues and limitations in the realm of carbonyl addition reactions with allenyl-, propargyl-, and vinylsilicon reagents, encompassing numerous practical as well as pedagogical principles is presented. Comparisons of chemo-, regio-, and stereoselectivity and reactivity are drawn. Synthetic applications and challenges associated with each class of organosilane are discussed threading together the prospects of these green carbanion surrogates.

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Section: Wwwchemeurjorgmentioning

confidence: 99%

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Long¹,

Aye

2009

Chemistry A European J

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“…Although the ring closure to form this strained system was expected to be challenging, the Prins reaction has been previously used for the preparation of bridging polycycles. 14 Tricycle 15 could be assembled through a bioinspired ortho -quinone methide hetero-Diels–Alder ( o -QMHDA) reaction between enol ether 17 and an o -QM generated from 16 . 15 Although o -QMHDA reactions are widely used to construct chroman frameworks, simple acyclic enol ethers or styrenes are typically employed as dienophiles, and are used in excess to avoid o -QM dimerization.…”

Section: Design Plan: First Generation Strategymentioning

confidence: 99%

Evolution of a Strategy for the Enantioselective Total Synthesis of (+)-Psiguadial B

et al. 2018

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(+)-Psiguadial B is a diformyl phloroglucinol meroterpenoid that exhibits anti-proliferative activity against the HepG2 human hepatoma cancer cell line. This full account details the evolution of a strategy that culminated in the first enantioselective total synthesis of (+)-psiguadial B. A key feature of the synthesis is the construction of the trans-cyclobutane motif by a Wolff rearrangement with in situ catalytic, asymmetric trapping of the ketene. An investigation of the substrate scope of this method to prepare enantioenriched 8-aminoquinolinamides is disclosed. Three routes toward (+)-psiguadial B were evaluated that featured the following key steps: 1) an ortho-quinone methide hetero–Diels–Alder cycloaddition to prepare the chroman framework; 2) a Prins cyclization to form the bridging bicyclo[4.3.1]decane system, and 3) a modified Norrish–Yang cyclization to generate the chroman. Ultimately, the successful strategy employed a ring-closing metathesis to form the seven-membered ring and an intramolecular O-arylation reaction to complete the polycyclic framework of the natural product.

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“…Thus, the acetoxyalkoxyacetic ester 281 cyclized under tin tetrachloride catalysis forming the corresponding tetrahydrooxepine 282 in moderate yield (Scheme 75) [106]. The same authors reported the cyclization of 5-alkenyl or 6-alkenyl acetals using tin tetrachloride as Lewis acid, forming the eight- [127] or nine-membered ring ethers, respectively [128]. The same authors reported the cyclization of 5-alkenyl or 6-alkenyl acetals using tin tetrachloride as Lewis acid, forming the eight- [127] or nine-membered ring ethers, respectively [128].…”

Section: Seven Eight and Nine Membered Rings Formationmentioning

confidence: 99%

The Prins Reaction: Advances and Applications

Pastor¹,

Yus

2007

COC

194

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The acid-catalyzed alkene-aldehyde condensation, known as the Prins reaction, is reviewed. Lewis acids, organic acids and supported catalysts have been reported to assist both the Prins acyclic reaction and the Prins cyclization. Acetals and oxocarbenium ions (generated from aldehydes and alcohols) have been described as reacting systems in the Prins reaction. Prins cyclizations have been used to form mainly five-and six-membered rings, albeit formation of seven to nine rings have been described. The Prins reaction (and cyclization) has been developed as a key strategic element in the total synthesis of different natural products. R O O 20 (55%): R = Cl 21 (35%): R = NHAc 14 (95%): R = H 15 (97%): R = Me 16 (88%): R = Cl 17 (65%): R = OMe 18 (99%): R = OAc 19 (56%): R = NHAc O O Cl 22 (81%) 24 (67%) 23 (80%)

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Preparation of eight-membered cyclic ethers by Lewis acid promoted acetal-alkene cyclizations

Cited by 96 publications

References 2 publications

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Evolution of a Strategy for the Enantioselective Total Synthesis of (+)-Psiguadial B

The Prins Reaction: Advances and Applications

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