Synthesis of N−H Bearing Imidazolidinones and Dihydroimidazolones Using Aza‐Heck Cyclizations
作者:Feiyang Xu、Scott A. Shuler、Donald A. Watson
DOI:10.1002/anie.201806295
日期:2018.9.10
The synthesis of unsaturated, unprotected imidazolidinones via an aza‐Heck reaction is described. This palladium‐catalyzed process allows for the cyclization of N‐phenoxy ureas onto pendant alkenes. The reaction has broad functional group tolerance, can be applied to complex ring topologies, and can be used to directly prepare mono‐ and bis‐unprotected imidazolidinones. By addition of Bu4NI, dihydroimidazolones
Synthesis of Cyclic
<i>N</i>
‐Hydroxylated Ureas and Oxazolidinone Oximes Enabled by Chemoselective Iodine(III)‐Mediated Radical or Cationic Cyclizations of Unsaturated
<i>N</i>
‐Alkoxyureas
作者:Laure Peilleron、Pascal Retailleau、Kevin Cariou
DOI:10.1002/adsc.201901135
日期:2019.11.19
In this study we describe the reactivity of unsaturated N‐alkoxyureas in the presence of different combinations of a hypervalent iodine(III) reagent and a bromide source or TEMPO. Three complementary cyclizations can be achieved depending on the reaction conditions. On the one hand, PIFA with pyridinium bromide leads to an oxybromination reaction. On the other hand, bis(tert‐butylcarbonyloxy)iodobenzene
Chasing the Proton Culprit from Palladium-Catalyzed Allylic Amination
作者:Igor Dubovyk、Iain D. G. Watson、Andrei K. Yudin
DOI:10.1021/ja076659n
日期:2007.11.1
We have found that the addition of base has a significant effect on palladium-catalyzed allylic amination. The long-standing problem of controlling the branched-to-linear ratio has been solved. In the presence of DBU and inexpensive, readily available ligands, palladium-catalyzed allylation proceeds under kinetic control, leading to high branched selectivity. Given the widespread utility of palladium-catalyzed allylic amination, we expect that these findings will be relevant in many areas ranging from asymmetric catalysis to target-oriented synthesis.
A novel synthetic route to 7-substituted derivatives of the antitumor agent LY231514 (MTA)
作者:Edward C. Taylor、Bin Liu
DOI:10.1016/s0040-4039(99)00959-4
日期:1999.7
This paper describes a further synthesis of the pyrrolo[2,3-d]pyrimidine antitumor agent MTA (LY231514). Manganic triacetate dihydrate-induced radical cyclization of methyl N-crotyl-N-(3',4'-dimethoxybenzyl)malonamide (4d) yielded the 3-carbomethoxy-2-pyrrolidinone 5d that was then thiated with P2S5 to the corresponding thiolactam (6d). Cyclization with guanidine gave the 7-substituted 2-amino-4(3H)-oxo5,6-dihydro-pyrrolo[2,3-d]pyrimidine (7d). Pd-catalyzed coupling with diethyl 4-iodobenzoylglutamate yielded (in a single step) the diethyl ester 9d. Deprotection with H2SO4/TFA followed by saponification then gave MTA. Several additional 7-substituted derivatives of MTA were prepared by use of this methodology. In contradiction to a published claim, these 7-substituted derivatives proved to be devoid of any significant cell growth inhibitory activity. (C) 1999 Elsevier Science Ltd. All rights reserved.