Total synthesis of the novel benzophenone NP-011694

Synthesis and Properties of V-Shaped Xanthene Dyes with Tunable and Predictable Absorption and Emission Wavelengths

“…V-shaped dyes 4 and 7 were synthesized according to the previously reported synthetic methods for compounds 2 and 3 (Scheme ). Protection of the phenolic hydroxy group in 9a as a methoxymethyl (MOM) ether gave 10a in 93% yield . Compound 10a was lithiated by treatment with butyllithium and then reacted with tri-MOM-protected xanthone 11 to afford coupling product 12a in 83% yield.…”

“…The MOM ester in compound 17 was hydrolyzed, and the resulting carboxylic acid was converted to the corresponding Weinreb amide to afford compound 18 in 76% yield over two steps . Compound 19 , was lithiated by treatment with n -BuLi and then reacted with Weinreb amide 18 to obtain key intermediate 20 in 42% yield. MOM-protected phloroglucinol 21 was lithiated with sec -BuLi and applied for the nucleophilic attack of key intermediate 20 , affording compound 22 in 34% yield.…”

“…A solution of n -BuLi (1.55 M n -hexane solution; 4.0 mL, 6.20 mmol) was added dropwise over 8 min to a solution of 19 , (2.15 g, 7.76 mmol) in dry THF (17 mL) under a nitrogen atmosphere at −78 °C. After stirring for 50 min, a solution of 18 (1.29 g, 5.17 mmol) in dry THF (10 mL) was added dropwise over 7 min to the mixture at −78 °C, and the resulting mixture was stirred at −78 °C for 15 min and 0 °C for 10 min.…”

“…10a: known 12 Compound 10b. To a stirred solution of 9b 13 (570.0 mg, 2.88 mmol) in dry DMF (15 mL), K 2 CO 3 (557.0 mg, 4.03 mmol) was added portion-wise.…”

“…Protection of the phenolic hydroxy group in 9a as a methoxymethyl (MOM) ether gave 10a in 93% yield. 12 Compound 10a was lithiated by treatment with butyllithium and then reacted with tri-MOM-protected xanthone 11 8 to afford coupling product 12a in 83% yield. Acid-mediated removal of the four MOM groups in compound 12a, followed by a pyran ring-forming reaction in water conducted in a sealed tube at high temperature (100 °C), gave the desired V-shaped dye 4 in 62% yield over two steps.…”