Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• ][1,2]oxaphosphocine 2-oxides 18 in good to excellent yields in DCM at room temperature for 4–8 h in the presence of the Grubbs 1st generation catalyst. Two naphthylene-fused (19 and 20), pyrimidine-2,4(1H,3H)-dione-fused (21), and 2H-chromen-2-one-fused (22) 1,2-oxaphosphocine 2-oxides were also

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• and synthetic chemistry. Compounds of this class have shown important activities, such as anticancer and antiparasitic, besides the commercially available drugs. These properties led to the development of efficient and greener synthetic methods to achieve the 2H-chromen-2-one core. In this context

• , the advances in asymmetric organocatalyzed synthesis of coumarin derivatives are discussed in this review, according to the mode of activation of the catalyst. Keywords: asymmetric synthesis; green chemistry; 2H-chromen-2-one; organocatalysis; Introduction Coumarins are important naturally occurring

DBU-promoted carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone

• Wen-Zhen Zhang,
• Si Liu and
• Xiao-Bing Lu

Beilstein J. Org. Chem. 2015, 11, 906–912, doi:10.3762/bjoc.11.102

• -diazabicycloundec-7-ene (DBU) is reported. This reaction provides convenient access to the biologically important compounds 4-hydroxy-2H-chromen-2-one and 4-hydroxy-2(1H)-quinolinone in moderate to good yields using carbon dioxide as the carboxylation reagent. An acyl migration from nitrogen to carbon is observed

• , the intramolecular carboxylative cyclization might provide a convenient access to 4-hydroxy-2H-chromen-2-one and 4-hydroxy-2(1H)-quinolinone. Indeed, Da Re and Sandri reported in 1960 that o-hydroxyacetophenone derivatives react with carbon dioxide (4 MPa) in the presence of 3 equivalents of potassium

• the 2H-chromen-2-one product (Table 2, entries 2 and 4). o-Hydroxyacetophenone bearing electron-donating alkyl and ether groups, or electron-withdrawing fluoro and bromo groups undergoes the carboxylative cyclization reaction smoothly, affording the corresponding 4-butoxy-2H-chromen-2-ones 2b–2f in

Synthesis of the fluorescent amino acid rac-(7-hydroxycoumarin-4-yl)ethylglycine

• Manfred Braun and
• Torsten Dittrich

Beilstein J. Org. Chem. 2010, 6, No. 69, doi:10.3762/bjoc.6.69

• by using Merck TLC Silicagel 60F254 aluminium sheets. Tetrahydrofuran (THF) was freshly distilled from sodium/benzophenone under a nitrogen atmosphere, and dichloromethane was freshly distilled from calcium hydride. 7-Hydroxy-4-(2-hydroxyethyl)-2H-chromen-2-one (3): A 500 mL flask was equipped with a

• ), 102.28 (C-8), 110.31 (C-4a), 111.46 (C-3), 112.78 (C-6), 126.44 (C-5), 154.58 (C-8a), 155.02 (C-4), 160.26 (C-7), 160.92 (C-2). 4-(2-Hydroxyethyl)-7-(t-butyldimethylsilyloxy)-2H-chromen-2-one (4): A 50 mL two-necked flask equipped with a magnetic stirrer and a connection to a combined nitrogen/vacuum

• ), 125.81 (C-5), 153.78 (C-8a), 155.62 (C-4), 159.66 (C-7), 161.86 (C-2). MS (EI, 70 eV): m/z (%) = 320 (M+, 45), 292 (20), 263 (100), 245 (70), 233 (35), 189 (35). Elemental anal. calcd. for C17H24O4Si: C, 63.72; H 7.55. Found: C, 63.60; H, 7.71. 4-(2-Bromoethyl)-7-(t-butyldimethylsilyloxy)-2H-chromen-2