Gold(I)‐Catalyzed Intramolecular Hydroamination of N‐Allylic N′‐Arylureas to form Imidazolidin‐2‐ones

Abstract

Treatment of N-allylic,N′-aryl ureas with a catalytic 1:1 mixture of di-tert-butyl-o-biphenylphoshphine gold(I) chloride and silver hexafluorophosphate (1 mol %) in chloroform at room temperature led to 5-exo hydroamination to form the corresponding imidazolidin-2-ones in excellent yield. In the case of N-allylic ureas that possessed an allylic alkyl, benzyloxymethyl, or acetoxymethyl substituent, gold(I)-catalyzed 5-exo hydroamination leads to formation of the corresponding trans-3,4-disubstituted imidazolidin-2-ones in excellent yield with ≥50:1 diastereoselectivity.

Synthesis of Saturated Heterocycles via Metal-Catalyzed Alkene Hydroamination or Hydroalkoxylation Reactions

“…On the other hand, substrates such as 30 containing the urea group within the tether cyclized to form imidazolidin-2-ones 31. Diastereoselectivities of >50:1 31-trans:31-cis were obtained for substrates bearing an alkyl group on the carbon linker [29]. Interestingly, the unprotected alcohol substrate 30e gave the cis product 31e as the major product in a 3.7:1 ratio.…”

Recent Advances in the Catalytic Synthesis of Imidazolidin-2-ones and Benzimidazolidin-2-ones

“…A less nucleophilic nitrogen leads to an increase in the enantiomeric excess and a loss in reactivity, which are both due to the less-favored final reductive elimination. Zhang in 2014 reported a gold(I)-catalyzed 5-exo-trig cyclization of N-allyl-N′-phenylurea followed by a gold (III) C-H functionalization to afford indoline products via formal [3 + 2] annulation [163]. Their optimized reaction conditions include [L7AuNTf2] (L7 = (4-CF3C6H4)3P) as a gold (I) source, selectfluor as an oxidant to afford the active species of gold (III) in THF, and water as additive to enhance the solubility of the oxidant in the reaction media.…”

“…Catalysts 2018, 8, x FOR PEER REVIEW 24 of 43 Scheme 47. Gold(I)-catalyzed 5-exo-trig cyclization followed by a gold III C-H functionalization [163].…”

New developments in gold-catalyzed manipulation of inactivated alkenes

“…When 39 was treated with a 1:1 mixture of 20a and AgPF 6 , imidazolidin-2-ones 40 were obtained in high yields under mild reaction conditions (Scheme 11) [47]. Analogously, substituted N- allylureas 41 provided 42 with high trans diastereoselectivity (dr = 50:1, Scheme 11).…”

“…The synthetic versatility of alkenyl ureas was further demonstrated by Widenhoefer employing slightly different substrates, namely N- allyl- N’- arylureas. When 39 was treated with a 1:1 mixture of 20a and AgPF 6 , imidazolidin-2-ones 40 were obtained in high yields under mild reaction conditions ( Scheme 11 ) [ 47 ]. Analogously, substituted N- allylureas 41 provided 42 with high trans diastereoselectivity (dr = 50:1, Scheme 11 ).…”