Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• more efficient reactions with alkene 88 (Table 6). In 2022, Oestreich reported the in situ formation of HCl by Lewis acid-induced Grob fragmentation of acid chloride 92 (Scheme 15B) [68]. The inconvenience of this method is that 92 has to be prepared in two steps, including a Birch reduction (Scheme

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• example, when esters 1a are subjected to Lewis acid-induced denitration, highly electron-deficient enones (reaction b) [4] are obtained. The latter compounds are highly reactive and undergo reaction with, e.g., mercaptoacetaldehyde affording thiophenes (reaction c) [5] or with activated (hetero)aromatic

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• reaction [34]. By installation of a triflyloxy group in the indole 5-position, Pd-catalyzed cyclization also would become possible. As an alternative to the cyclization of enones, Lewis acid-induced cyclizations of allylic alcohols could afford the desired cyclopenta[f]indole system (C, D). Here, it was

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• -allene. The Lewis acid-induced rearrangement of this heterocycle provided the corresponding bicyclic 1,2-oxazine derivative that may be regarded as internally protected amino sugar analogue. After subsequent reduction of the carbonyl group, the resulting bicyclic compound was used for Suzuki cross

• bicyclic 1,2-oxazine derivative 3 was used as key building block for the Suzuki cross-coupling reaction to synthesize p-terphenyl-linked derivatives 1. The key intermediate 3 was prepared by a Lewis acid-induced rearrangement of 3,6-dihydro-2H-oxazine 4, that origins from a stereoselective [3 + 3

• prepared in six steps with an overall yield of 46%. The diastereomers can easily be separated by column chromatography, but this turned out not to be mandatory. The next step of our anticipated sequence, the Lewis acid-induced rearrangement, converts the dioxolane C-2 carbon into an sp2-hybridized carbon

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• enantiopure nitrones and lithiated TMSE-allene we prepared three 1,2-oxazine derivatives which underwent a highly stereoselective Lewis acid-induced rearrangement to give bicyclic products in good yield. Subsequent reductive transformations delivered a library of new poly(hydroxy)aminooxepane derivatives. The

• crucial final palladium-catalyzed hydrogenolysis of the 1,2-oxazine moiety was optimized resulting in a reasonably efficient approach to a series of new seven-membered carbohydrate mimetics. Keywords: aminooxepanes; carbohydrate mimetics; hydrogenolyses; Lewis acid-induced; lithiated allenes; nitrones

• sp2-hybridized carbon during the Lewis acid-induced ring opening, the configuration of syn-10 was not assigned at this center. We discussed the mechanism of this [3 + 3]-cyclization in detail including possible side-reactions in an earlier report [31]. The observed high syn-diastereoselectivities are

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• diastereoisomers. The Lewis acid induced key step, a domino epoxide-opening/rearrangement/cyclization cascade, most likely proceeded in a stepwise manner via intermediate 179. Activation of the epoxide with boron trifluoride etherate induces the planned sigmatropic [1,2]-methyl and [1,2]-hydride shifts to generate

• decalin moiety has formed, two sigmatropic, stereospecific [1,2]-shifts of intermediate 170 provide the tertiary carbocation 171, which could be trapped by the phenolic alcohol to give stachyflin (156) [143]. In 2011, the first enantioselective total synthesis of (+)-stachyflin (156) via a Lewis acid

• induced domino epoxide-opening/rearrangement/cyclization cascade was accomplished by the group of Katoh (Scheme 22) [144]. The synthesis commenced with the conversion of dimethyl 2,6-dihydroxyterephthalate (172) to nitrile 173 within five consecutive steps. Hydrogenation and lactam formation of 173 gave

Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

• Florian Boeck,
• Max Blazejak,
• Markus R. Anneser and
• Lukas Hintermann

Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186

• isomerization/cyclization [17]. (c) Lewis acid induced demethylation/cyclization [18]. Hypothetical catalytic cycle: Nucleophile-assisted cyclization of (E)-ethyl 2’-hydroxycinnamate (1) to coumarin (2). Proposed catalytic cycle, based on 31P NMR spectroscopic and color evidence. Screening of catalysts for

Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

• Fabian Pfrengle and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 75, doi:10.3762/bjoc.6.75

• efficient preparation include Prins cyclizations, intramolecular substitutions, ring closure metathesis, and hetero Diels–Alder reactions [1][2]. Our group recently reported the synthesis of enantiopure aminopyrans employing as the key step a Lewis acid induced rearrangement of 1,2-oxazines to bicyclic

• suitable substrates for Lewis-acid induced cyclizations furnishing mono-, di-, or spirocyclic dihydropyrans. Subsequent reactions such as bromination, acidic hydrolysis or dihydroxylation provided differently substituted and configured pyranone derivatives as precursors for the stereoselective synthesis of

• . The combined organic phases were dried (Na2SO4) and the solvent was removed in vacuo. Purification by column chromatography (silica gel, hexane/EtOAc = 20:1) yielded the products as colourless oils. Lewis acid-induced cyclization of 1,3-dioxolanyl-substituted enol ethers To a solution of the

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• into 75 by protection of the OH group with TBDPSCl and saponification of the benzoate ester (LiOH). Lewis acid-induced glycosylation [46] of 75 with trichloroacetimidate 76 gave 77. The latter was then subjected to TBAF deprotection, PCC oxidation, and Pd/C hydrogenation, to afford analog 78. Isopentyl

• ) [50], Miller [(TMS)2NH, TMSI] [51], and Lewis acid-induced (ZnCl2, TiCl4) [52][53] conditions. The ketone also resisted the action of specialized reagents such as N,O-bis(trimethylsilyl)acetamide and N,O-bis(trimethylsilyl)trifluoroacetamide [54][55]. Ultimately, the desired compound 101 was obtained