A case study of the MAC (masked acyl cyanide) oxyhomologation of <i>N</i>,<i>N</i>-dibenzyl-<scp>l</scp>-phenylalaninal with <i>anti</i> diastereoselectivity: preparation of (2<i>S</i>,3<i>S</i>)-allophenylnorstatin esters
作者:Xuefeng He、Marie Buchotte、Régis Guillot、Sandrine Deloisy、David J. Aitken
DOI:10.1039/d1ob02411f
日期:——
The three-component reaction proceeds with unhindered alcohols in good yield and high anti diastereoselectivity to give protected ester derivatives of (2S,3S)-allophenylnorstatin and provides an expedient access to the amino acid itself.
An alternative method for the preparation of MAC reagents, H-C(CN)2O-R, was developed. Using the proposed method, MAC reagents with acyl moiety were synthesized from malononitrile in more than 60% overall yields in three steps.
Squaramide Organocatalyzed Addition of a Masked Acyl Cyanide to β-Nitrostyrenes
作者:Alison P. Hart、Caroline J. DeGraw、Gavin J. Rustin、Matthew G. Donahue、Julie A. Pigza
DOI:10.1021/acs.joc.3c01838
日期:2023.12.1
A method for the squaramide-organocatalyzed enantioselective addition of a silyl-protected masked acyl cyanide (MAC) reagent to various β-nitrostyrenes is described. Reactions are carried out in a freezer and provide products cleanly and in high enantioselectivities at very low catalyst loadings. Adducts are then unmasked, providing various oxidation state 3 functional groups, thereby highlighting
描述了一种甲硅烷基保护的掩蔽酰基氰化物 (MAC) 试剂在方酰胺有机催化下对映选择性加成到各种 β-硝基苯乙烯上的方法。反应在冷冻机中进行,以非常低的催化剂负载量提供清洁且具有高对映选择性的产品。然后,加合物被揭开,提供各种氧化态 3 官能团,从而突出这些 MAC 试剂的实用性和制备 β-氨基酸的新策略。
On the Keto‐Enol‐Tautomerism of 2‐(1‐Hydroxyethylidene)malononitrile and Its Lewis Adduct Formation with B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>
Using NMR techniques and SCXRD, it is proven that 2-(1-hydroxyethylidene)malononitrile exists exclusively as the enol isomer in solution as well as in the solidstate. Additionally, the Lewisacid mono- and diadduct of the enol with B(C6F5)3 as Lewisacid are fully characterized. DFT as well as CC calculations underline the preference of the enol isomer in the tautomeric equilibrium.
使用NMR技术和SCXRD,证明2-(1-羟基亚乙基)丙二腈在溶液和固态中仅以烯醇异构体存在。此外,还充分表征了烯醇与作为路易斯酸的B(C 6 F 5 ) 3的路易斯酸单加成物和二加成物。DFT 和 CC 计算强调了互变平衡中烯醇异构体的偏好。
Libis,B.; Fleury,J.-P., Bulletin de la Societe Chimique de France, 1965, p. 3323 - 3329