4746-87-6Relevant articles and documents
Hydration of Cyanohydrins by Highly Active Cationic Pt Catalysts: Mechanism and Scope
Li, Chengcheng,Chang, Xiao-Yong,Huo, Luqiong,Tan, Haibo,Xing, Xiangyou,Xu, Chen
, p. 8716 - 8726 (2021/07/26)
Cyanohydrins (α-hydroxy nitriles) are a special type of nitriles that readily decompose into hydrogen cyanide (HCN) and the corresponding carbonyl compounds. Hydration of cyanohydrins that are readily available through cyanation of aldehydes and ketones provides the most straightforward route to valuable α-hydroxyamides. However, due to low stability of cyanohydrins and deactivation of the catalysts by the released HCN, catalytic direct hydration of cyanohydrins still remains largely unsolved. As a general trend, cyanohydrins containing bulkier substituents, such as α,α-diaryl cyanohydrins, degrade more quickly and thus are more difficult to be hydrated. Here, we report development of cationic platinum catalysts that exhibit high reactivity for hydration of various cyanohydrins. Detailed mechanistic investigations for hydration of nitriles by (PμP)Pt(PR2OH)X(OTf) reveal a catalytic cycle involving the formation of a five-membered metallacyclic intermediate and subsequent hydrolysis via attacking on the phosphorus of the secondary phosphine oxide (PR2OH) ligand by H2O. We discovered that Pt catalyst A bearing the electron-rich, appropriately small-bite-angle bisphosphine ligand provides super reactivity for hydration of cyanohydrins. The hydration reactions catalyzed by A proceed at ambient temperatures and occur with a wide variety of cyanohydrins, including the most difficult α,α-diaryl cyanohydrins, with good turnover numbers.
Catalytic Transfer Hydration of Cyanohydrins to α-Hydroxyamides
Kanda, Tomoya,Naraoka, Asuka,Naka, Hiroshi
, p. 825 - 830 (2019/01/14)
We report the palladium(II)-catalyzed transfer hydration of cyanohydrins to α-hydroxyamides by using carboxamides as water donors. This method enables selective hydration of various aldehyde- and ketone-derived cyanohydrins to afford α-mono- and α,α-disubstituted-α-hydroxyamides, respectively, under mild conditions (50 °C, 10 min). The direct conversion of fenofibrate, a drug bearing a benzophenone moiety, into a functionalized α,α-diaryl-α-hydroxyamide was achieved by means of a hydrocyanation-transfer hydration sequence. Preliminary kinetic studies and the synthesis of a site-specifically 18O-labeled α-hydroxyamide demonstrated the carbonyl oxygen transfer from the carboxamide reagent into the α-hydroxyamide product.
Reactions of Trimethylsilyl Azide with Heterocumulenes
Tsuge, Otohiko,Urano, Satoshi,Oe, Koji
, p. 5130 - 5136 (2007/10/02)
Trimethylsilyl azide (TMSA) reacted with aryl isocyanates to give arylcarbamoyl azides, 1-aryl-5(4H)-tetrazolinones, and / or 1-aryl-4-(arylcarbamoyl)-5(4H)-tetrazolinones, whose yields were dependent on the reaction conditions.The reaction between TMSA and benzoyl or thiobenzoyl isocyanates provides a facile method for the preparation of 5-aryl-3-hydroxy-1,2,4-oxadiazoles or -1,2,4-thiadiazoles, respectively.However, with phenyl or benzoyl isothiocyanate, 1-anilino-1,2,3,4-thiatriazole or benzoylcyanamide was obtained in low yield, respectively.TMSA reacted with carbodiimides to afford the corresponding 5-aminotetrazoles.Tetraphenylsuccinimide, N-(diphenylacetyl)tetraphenylsuccinimide, 1,3-bis(diphenylmethyl)urea, and / or benziloylamide were obtained from the reaction of TMSA with diphenyl ketene.The pathways for the formation of the above products are also described.
