Science of Synthesis

Hopkinson, M. N.; Gouverneur, V., Science of Synthesis Knowledge Updates, (2011) 2, 124.

Although more widely observed with alkynes and allenes, under certain conditions, gold catalysts can activate alkenes toward nucleophilic attack. As with other multiple bonds activated by gold, in the vast majority of cases the organogold intermediate generated during these reactions undergoes protodeauration to afford the product of hydrofunctionalization. This pathway can be intercepted during the gold(I)-catalyzed intramolecular amination of alkenyl ureas ‌54‌ by the addition of (diacetoxyiodo)benzene.[‌79‌] Under these conditions, a second amination step by the other urea nitrogen occurs, leading to 1,2-diaminated products ‌55‌ (‌Scheme 23‌). The catalyst of choice for this transformation is acetoxy(triphenylphosphine)gold(I) (7.5 mol%), which delivers the cyclic product ‌55‌ (R1 = Me; R2 = H) in 90% yield when reacted with the corresponding alkene ‌54‌ (R1 = Me; R2 = H) in the presence of the oxidant (1.2 equiv) and sodium acetate (0.5 equiv). The cascade 5-exo-trig cyclization–oxidative amination process can be applied to a wide-range of alkyl- and aryl-substituted terminal alkenes with excellent yields. Importantly, the free 1,2-diamines can easily be liberated from the urea upon treatment with sodium amalgam and lithium aluminum hydride.

‌Meeeee 88‌ Meeeeeeee Meeeeeeeeee ee Meeeeee[‌88‌]

‌Meeeeeeeeee 88‌

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‌Meeeee 88‌ Meeeeeeee Meeeeeeee eee Meee-Meeeeeeee Meeeeeeee Meeeeeeeeee ee Meeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeeeeeeeeeee-8M-eeeeeee[8,8-e]eeeeeeee-8-eeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

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