Orthogonally protected dialkynes

Synthesis of deuterium and 15N‐labelled 2,5‐Bis[5‐amidino‐2‐pyridyl]furan and 2,5‐Bis[5‐(methoxyamidino)‐2‐pyridyl]furan

“…A Stille coupling reaction of two equivalents of 7 with one equivalent of 2,5-bis[tri-n-butyltin]-furan-d 0 at 70-808C furnished the dibromo-compound 8, the regioselectivity of 7 is consistent with similar reactions reported previously for 2,5-dibromopyridine-d 0 . 13,[19][20][21][22] Cyanation of 8 with Cu(I)CN at 140-1508C gave the dinitrile 9. Treatment of 9 with hydroxylamine hydrochloride and potassium tert-butoxide in DMSO at ambient temperature gave the diamidoxime 11 in 93% yield.…”

Silicon- and germanium-substituted propynals as ambident electrophiles for the design of new heterocycles and polyfunctional acetylenes

“…However, the synthesis of functionally substituted 1,2 di hydropyridines is a nontrivial problem, they predomi nantly are obtained by reduction 173 or functionalization 174 of pyridine derivatives. (45) in 98% yield. 177 We suggest (Scheme 23) that the reaction begins with nucleophilic addition of water to the triple bond of propynal 2a and formation of malondialdehyde (46) Similar trimerization of unsubstituted propynal 2i is described in papers, 179,180 however, the authors do not suggest a scheme for its formation.…”

“…44 Apparently, this can be explained by the heterolysis of the Ge-C sp bond in com pound 2b under the oxidation conditions (instability of germaniumacetylenic compounds toward acids is well known). 45 To sum up, despite of the same efficiency of both oxidants in the oxidation of alcohols 1a,b, MnO 2 /SiO 2 is more suitable for the synthesis of propynals 2a,b under MW irradiation.…”

Protection for the Alkyne CH

“…Bu 4 NF, THF, rt, quant 16. THF, 88% yield 23. Bu 4 NF, 0.4 eq., THF, MeOH, Ϫ20ЊC to Ϫ10ЊC, 98% yield 17.…”