The cyclopropylcarbinyl route to γ-silyl carbocations

• Xavier Creary

Beilstein J. Org. Chem. 2019, 15, 1769–1780, doi:10.3762/bjoc.15.170

• CF3 group is trans to the TMS group in the isomer 59. Additional cyclopropylcarbinyl systems containing the electron-withdrawing cyano and carbomethoxy groups were prepared in an analogous fashion as shown in Scheme 13. Carbomethoxycyano carbene addition to vinyltrimethylsilane followed by lithium

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• cyclopropanol by Cottle [7], the most popular methods for the preparation of cyclopropanols rely on the transformation of enolates [8][9], silyl enol ether [10][11][12], vinyl borane [13][14][15][16][17], Fischer carbene addition [18], addition of nucleophiles to carbonyl groups [19][20][21][22][23][24][25

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• copolymerization of ethylene and ethyl diazoacetate with rhodium-based catalysts (Scheme 2a). Ethyl cyclopropanecarboxylate has been prepared in several ways, alternative to the direct carbene addition to ethylene (Scheme 2b): ring contraction of 2-halocyclobutanone [5], cyclization of alkyl 4-halobutanoates [6

• equiv of AgOTf with respect to the gold complex resulted in low consumption of EDA, and minor amounts of 1, olefins 2 and cyclopropane 3 derived from carbene addition to 2 were detected. The use of AgSbF6 led to different results: the yield into desired 1 increased up to 25% but the functionalization of

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

• Gisela V. Saborit,
• Carlos Cativiela,
• Ana I. Jiménez,
• Josep Bonjoch and
• Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

• takes place from polyfunctionalized cyclohexanones or related compounds through a Michael reaction [7], successive inter- and intramolecular radical processes [8], intramolecular carbene addition/cyclization [9][10], aldol cyclizations either under Lewis acid catalysis [11] or from diazoketones in the

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• synthesis via dihalocarbene addition: Probably one of the most useful methods for the synthesis of halo-benzotropones is the formation of a three-membered intermediate by addition of halocarbenes to alkoxynaphthalenes. The carbene addition step is then a simultaneous ring-opening step to give the

• via carbene addition are shown in Table 2. As shown in Table 2, the reported yields were extremely low. To further improve the yields of the products, different carbene sources and reaction conditions were tested. Parham’s group reported treatment of 2-methoxynaphthalene (306) with 0.75 equivalents of

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

• Jerzy Zakrzewski and
• Bogumiła Huras

Beilstein J. Org. Chem. 2015, 11, 1155–1162, doi:10.3762/bjoc.11.130

• recognized (e.g., reductions, acidic medium, carbene addition, etc.). Because we would like to check the possibility of performing the Mizoroki–Heck cross-coupling reaction with nitroxides, herein the synthesis of cinnamates bearing a nitroxyl moiety is presented using aryl iodides as exemplary test

Synthesis of 2,6-disubstituted tetrahydroazulene derivatives

• Zakir Hussain,
• Henning Hopf,
• Khurshid Ayub and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 693–698, doi:10.3762/bjoc.8.77

• route by using carbene adduct intermediates. The protocol can be applied for the construction of functionalized hydroazulene skeletons as key components of many natural products as well as the core system of novel liquid-crystalline materials. Keywords: carbene addition; hydroazulenes; liquid crystals

• '-carbonyldiimidazole, tert-butyl alcohol and DBU to afford ester 3 in quantitative yield. The ester 3 was then subjected to carbene addition by treatment with ethyl diazoacetate in the presence of a copper catalyst [17] in THF under reflux. The carbene adduct 4 was obtained as the major product, as a colorless oil in

• double bond of the substrate. It is worth mentioning that in our earlier work on similar compounds [19], we isolated at least two isomers of 4 (with the methine hydrogen atom at the five-membered ring being present at either the α or β position). In our earlier work [10], carbene addition to similar