Synthesis of Photoaffinity Derivatives of Adenophostin A

Abstract

Photoaffinity derivatives 7 and 8 of adenophostin A, modified at the 5′‐ and 1′‐positions, were prepared by a chemoselective reaction of the aminophostins 15 and 30 with N‐succinimidyl p‐benzoyl‐2,3‐dihydrocinnamate (p‐benzoyldihydrocinnamoyl‐N‐hydroxysuccinimide; BZDC‐NHS, 21). The latter compound was prepared by Heck coupling of 4‐iodobenzophenone (16) with methyl acrylate.

Contribution of Phosphates and Adenine to the Potency of Adenophostins at the IP3 Receptor: Synthesis of All Possible Bisphosphates of Adenophostin A

“…Such a high degree of selectivity has been observed before when structurally similar compounds were used. 25 , 27 , 28 To make the disaccharide donor for Vorbrüggen glycosylation, the isopropylidene group in 17 was hydrolyzed with 90% trifluoroacetic acid (TFA), and the resulting mixture of diols (anomeric mixture) was acetylated under standard conditions to produce a chromatographically inseparable α/β mixture of triacetates 18 . Vorbrüggen condensation of 18 with silylated 6-chloropurine gave the β-nucleoside 19 as the exclusive product.…”

Carbamoyl-Substituted N-Heterocyclic Carbene Complexes of Palladium(II): Application to Sonogashira Cross-Coupling Reactions

“…For example, Et 3 N, i Pr 2 NH, and K 2 CO 3 gave only 27%, 25%, and 4% conversion, respectively, after 24 h at 80 °C. The use of Na 2 CO 3 or K 2 CO 3 as a base have also been reported by several research groups as modified procedures for Sonogashira reactions. However, this is the first time to our knowledge that Cs 2 CO 3 has been used as a base to increase the rate of Sonogashira reactions, although it is now widely used in other Pd-catalyzed cross-coupling reactions.…”

Highly Satisfactory Procedures for the Pd-Catalyzed Cross Coupling of Aryl Electrophiles with in Situ Generated Alkynylzinc Derivatives

“…Despite its overall excellence, however, various difficulties have also been noted. One widely reported is that, under the standard conditions, electron-deficient alkynes, such as HC⋮CCOOR, where R is Me, Et, and so on, 1-propyn-3-ones,5h and HC⋮CCF 3 , tend to give their arylated and alkenylated derivatives in unacceptably low yields. Various modifications have been devised to overcome this difficulty.…”

“…Various modifications have been devised to overcome this difficulty. They include the use of (a) propynoic acid readily convertible in situ to electron-rich propynoate anion, 5a,b (b) 3,3,3-tris(ethoxy)-1-propyne in place of ethyl propynoate, and (c) K 2 CO 3 5d,e,g,h or Na 2 CO 3 5f as a base in place of amines. These modifications are, however, indirect 5a,b,7 and hence somewhat cumbersome and/or of unpredictable and limited applicability. 5d-f The most recent modification 5h published during the course of this investigation does appear to represent an exception, but the use of preformed iodonium salts requiring both aryl iodides and sulfonates adds an extra step and poses a question of how to attain the aryl/alkyne ratio of 1:1.…”