Formylation of Benzopyrones. I. Formylation of Hydroxycoumarins with Hexamethylenetetramine¹

A self-immobilizing and fluorogenic unnatural amino acid that mimics phosphotyrosine

“…Subsequently, formylation of 6 by Duff's reaction gave 7 in moderate yield (25%). 10 Next, phosphorylation with di(2-nitrobenzyl) chlorophosphate under basic conditions provided 8 (46% yield), which was reduced with NaBH 4 (giving 9; 85% yield), followed by fluorination with DAST to give 10 (74% yield). Finally, the allyl group in 10 was removed by treatment with Pd(PPh 3 ) 4 , giving 11 (90% yield).…”

Photo- and ionochromic indoline spiropyrans based on 7,8-dihydroxy-4-methyl-2-oxo-2H-chromene-6-carbaldehyde

“…Signals from diastereotopic methylene protons in the N-benzyl substituent of compound IIb appeared as an AB quartet (two doublets at δ 4.25 and 4.58 ppm with a coupling constant 2 J of 16.50 Hz). Diastereotopic protons in the methyl groups of the N-isopropyl substituent of IIc DOI: 10 These findings indicated cyclic structure of the condensation products. The 7-H proton resonated as a singlet at δ 6.12-6.13 ppm, protons in the 6-methyl group gave a singlet at δ 2.38-2.39 ppm, and signal from the 10-OH proton was located at δ 5.45-5.60 ppm.…”

“…In the present article we describe the synthesis and properties of spiropyrans possessing an additional ligand center, hydroxy group in position 10 of the pyranochromene fragment. 7,8-Dihydroxy-4-methyl-2-oxo-2H-chromene-6-carbaldehyde (I) was synthesized according to the procedure reported in [10]. Condensation of aldehyde I with N-substituted 2,3,3-trimethyl-3H-indol-1-ium perchlorates in the presence of triethylamine gave the corresponding spiropyrans IIa-IIe (Scheme 1).…”