Alkyne hydroamination triggered cyclizations: A powerful tool for the construction of biologically important structural motifs

“Anti-Michael addition” of Grignard reagents to sulfonylacetylenes: synthesis of alkynes

“…The reaction mixture was stirred, at temperature indicated in each case, until the total consumption of sulfone (monitored by TLC 6 : 1, chex : AcOEt). The reaction mixture was treated with a saturated solution of NH 4 Cl and extracted with Et 2 O. The resulting residue was purified by silica gel flash chromatography (solvents indicated in each case).…”

“…1, 2 The triple bond is extremely important in the assembly of different nano-scale molecules, such as fullerenes, nano-tubes or porphyrins. Moreover, the triple bond moiety has been employed as a starting material for a large number of different reactions, such as click chemistry, 3 alkyne hydroamination, 4 Pd-catalyzed cross-coupling, 5 olefin metathesis, 6 and [2 + 2 + 2] cycloaddition arene formation. 7 In the last decade, the 1,3-dipolar cycloadditions of azides and alkynes have been used in polymer and materials sciences, 8 in biology, 9 and in medicinal chemistry 10 (bioconjugates).…”

An efficient access to novel 2H-pyrazino[2,1-b]quinazoline-1,6-diones via intramolecular alkyne hydroamination

“…Nevertheless, we anticipated that subjecting these amides to reaction conditions that are typically employed for the anti-Markovnikov hydration of alkynes 4 should permit the desired ring closure reaction between the amide nitrogen and the propargyl residue. Here, we wish to report on the application of this concept (known as alkyne hydroamination triggered cyclization 5 ) for the convenient synthesis of a small series of novel 3-methyl-2H-pyrazino[2,1-b]quinazoline-1,6-dione derivatives that represent an interesting new molecular scaffold.…”

“…The latter apparently suffers from decreased nucleophilicity because of protonation of the pyridine nitrogen in the strongly acidic medium. Regardless of the actual reaction mechanism (alkyne hydration and then cyclization of the enolic form versus addition of the amide oxygen and subsequent partial hydrolysis of the cyclic imidate), ring closure with concomitant loss of 4-aminopyridine in any case affords the tricyclic oxazinone (5).…”

Microwave-Assisted Synthesis and Characterization of [Rh2(OAc)4(L)2] Paddlewheel Complexes: A Joint Experimental and Computational Study

“…Based on the properties of the catalyst, this reaction can afford either the Markovnikov or anti-Markovnikov products ( Figure 2) [52][53][54][55][56][57][58]. Furthermore, a few Rh species have been reported as excellent catalysts for this process [59][60][61][62][63].…”