Electrogenerated base-promoted cyclopropanation using alkyl 2-chloroacetates

• Kouichi Matsumoto,
• Yuta Hayashi,
• Kengo Hamasaki,
• Mizuki Matsuse,
• Hiyono Suzuki,
• Keiji Nishiwaki and
• Norihito Kawashita

Beilstein J. Org. Chem. 2022, 18, 1116–1122, doi:10.3762/bjoc.18.114

• colleagues reported in 2000 that the reaction between a Michael acceptor such as diethyl fumarate and a sulfur-ylide, prepared from ethyl 2-diazoacetate and tetrahydro-2H-thiopyran in the presence of Cu(acac)2, yielded triethyl cyclopropane-1,2,3-tricarboxylate in 68% yield (Scheme 1, reaction 1) [10]. The

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• -promoted double bond migration. The cyclopropyl functionality in 46 can be assembled from the reaction of sulfur ylide and the α,β-unsaturated ketone 47, which in turn can be realized from the cross metathesis between commercially available ethyl vinyl ketone (48) and the C2-symmetrical diene-diol 49. The

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• facile preparation of thienyl heterocycles 8. The mechanism for this reaction is based on the formation of a sulfur ylide-like intermediate. It was clearly suggested by (i) the intramolecular cyclization of ketene N,S-acetals 7 to the corresponding thiophenes 8, (ii) 1H NMR studies of Meldrum’s acid

• -substituted aminothioacetals 9, and (iii) substitution studies of the methoxy group on Meldrum’s acid containing N,S-acetals 9b. Notably, in terms of structural effects on the reactivity and stability of sulfur ylide-like intermediates, 2-pyridyl substituted compound 7a exhibited superior properties over

• those of others. Keywords: 5-(heterocyclic)thiophenes; one-pot sequential synthesis; sulfur ylide; tetrasubstituted thiophene; Introduction Since the discovery of stable sulfonium ylides 1 in 1930 [1] and the pioneering work of several research groups during the 1960s (2 and 3) [2][3][4][5][6][7][8][9

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• . In contrast to the nucleophilic dimethoxycarbene, the formal transfer of the bis(carbomethoxy)carbene from the sulfur ylide 12 to E-1a leads to the cyclopropane derivative 13 [23] (Scheme 4). The reaction was proposed to occur stepwise via the zwiterrionic intermediate 14. Another example of a

• thiophene derived sulfur ylide 12. Cyclopropanation of dimethyl dicyanofumarate (E-1b) through a stepwise reaction with the in situ generated thiocarbonyl S-isopropanide 16a. The [2 + 2]-cycloadditions of dimethyl dicyanofumarate (E-1b) with electron-rich ethylenes 20 and 22. The [2 + 2]-cycloaddition of

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• muraymycin core structure (Scheme 6) [78][99]. The key step of their route was a sulfur-ylide reaction with high substrate-controlled diastereoselectivity [100][101][102]. This epoxide-forming sulfur-ylide reaction had been established before by Sarabia et al. [103][104]. After some initial confusion

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• -thiones 19 [38]. These reactions (Scheme 3 and Table 1) use an excess of 19 to minimise the formation of 5a as a byproduct, making it possible to isolate tosylated MPTTFs (such as 4a–f) in high yields. This is believed to be due to the higher reactivity of sulfur ylide intermediates (formed from 1,3

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

• Akihiro Shimizu,
• Ryutaro Hayashi,
• Yosuke Ashikari,
• Toshiki Nokami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

• part of the resulting sulfur ylide abstracts a proton attached to the carbon adjacent to the oxygen to give α-bromoketone 4a-Br by the Swern–Moffatt-type oxidation mechanism [23][24][25][26][27]. On the other hand, the hydroxide ion attacks the sulfur atom in 3a-Br and cleaves the S–O bond to give the

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• ]. Treatment of 20 with the sulfur ylide derived from trimethylsulfoxonium iodide [33][34] led to recovery of starting material at room temperature, but decomposition at elevated temperatures. Instead, the enone was smoothly reduced to the allylic alcohol, and a Furukawa-modified Simmons–Smith reaction [35

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• structures, see Figure 16) were inert to the ylide 21 [49]. When we combined the pregenerated iminium salts 3a–e with the sulfur ylide 21, the expected cyclopropanes 23 were indeed formed in good yield, although with low diastereo- and enantioselectivity (Figure 14) [64]. Even the rate constants calculated

• by Equation 1 agreed, within the general tolerance, with the experimental values; with one exception. The iminium intermediate derived from indole-2-carboxylic acid (3g) reacted at least 105 times faster with the sulfur ylide 21 than calculated by Equation 1, which can be explained by electrostatic

• activation as initially proposed by MacMillan (Figure 15) [49]. Thus, the failure of the imidazolidinones 1a and 1b to catalyze cyclopropanations with the sulfur ylide 21 is not due to the low reactivities of sulfur ylides toward iminium ions, but is due to the high Brønsted basicity of the sulfur ylides 24

Reagent controlled addition of chiral sulfur ylides to chiral aldehydes

• Varinder K. Aggarwal and
• Jie Bi

Beilstein J. Org. Chem. 2005, 1, No. 4, doi:10.1186/1860-5397-1-4

• (dimethylamino)-phosphoranylidene]-phosphoric triamide ethylimine,) [4][5] (sulfur ylide 4) was initially investigated to establish the degree of substrate control. This furnished a mixture of 3 epoxides 7a, 7b, and 7c in a 37:14:49 ratio (Table 1, entry 1). The cis and trans isomers are easily distinguished by

• , has been reported to give exclusively the trans epoxide 9 but again as an 86: 14 ratio of diastereoisomers.[7] We then turned our attention to reactions of the two chiral sulfur ylide enantiomers ((+)-1/(-)-1) with aldehyde 3 (Table 1, entry 3 and 5). Interestingly, in both cases, high levels of

• independently when betaine formation is non-reversible. Although we are able to modify the reaction conditions to make betaine formation less reversible, no methods are available at present to make it more reversible. In conclusion, reaction of the chiral sulfur ylide 1 with the chiral aldehyde glyceraldehyde