Total synthesis of Hirtellanine A

Synthesis and Transformation of Halochromones

“…3-Iodo-5-methoxy-8,8-dimethyl-8H-pyrano[3,2-g]chromone 25 can be efficiently prepared by C-ring opening of chromone 23 with piperidine in MeOH and subsequent treatment with iodine in the presence of pyridine (Scheme 8) [76].…”

“…The isoflavone skeleton in the convergent total synthesis of kwakhurin was constructed by Suzuki-Miyaura coupling of the appropriate 3-bromochromone and arylboronic acid in the presence of tetrabutylammonium bromide as additive [167]. A one-pot sequential boronation and Suzuki-Miyaura crosscoupling protocol of 3-iodo-5-methoxy-8,8-dimethylpyrano[3,2-g]chromen-4(8H)-one 120 allowed to obtain a substituted isoflavone-type compound 121 in an excellent overall yield avoiding the stability issue of borate ester (Scheme 40) [76]. In the total synthesis of glaziovianin A, a powerful antitumor isoflavone, and various of their pharmacological active analogues a similar procedure was used in the Suzuki-Miyaura cross-coupling reaction of iodochromones and stable arylboronates [168,169].…”

Synthesis of Heterocycle‐Bridged Peptidic Macrocycles through 1,3‐Diyne Transformations

“…[7] The reaction of 1,3-diynes with S-nucleophiles can lead to thioenynes or thiophenes, [8][9][10][11][12][13][14][15][16] and analogous hydration or hydroamination reactions give rise to furans [15][16][17][18] or pyrroles. [12,15,[17][18][19][20] Unfortunately, in many cases a high reaction temperature is needed, and these transformations are mostly reported by using arylated 1,3-diynes. It has been shown that related reactions of alkyl-substituted 1,3-diynes often result in a drastic drop in yield relative to those obtained for aromatic substituted thiophenes [8] or furans.…”

Studies on the Total Synthesis of Hirtellanine A: Regioselective Synthesis of Benzopyran

“…[1][2][3][4][5] Most of these flavonoids strongly inhibited mitogen-induced splenocyte proliferation. [7] [a] School Houben-Hoesch reaction of aryl cyanide 3 with phloroglucinol, a one-pot sequential boronation, a Suzuki-Miyaura cross-coupling of aryl bromide 33 with aryl iodide 26, and a base-mediated regioselective Claisen rearrangement for the benzopyran construction. Compared with Cyclosporin A, Hirtellanine A has a higher B lymphocyte suppression activity and a lower cytotoxicity.…”

“…In this paper, we document the results of our studies towards the first total synthesis of Hirtellanine A. [7] [a] School Houben-Hoesch reaction of aryl cyanide 3 with phloroglucinol, a one-pot sequential boronation, a Suzuki-Miyaura cross-coupling of aryl bromide 33 with aryl iodide 26, and a base-mediated regioselective Claisen rearrangement for the benzopyran construction.…”