Crystal structures of proline-derived enamines.
نویسندگان
چکیده
The isolation and structural characterization of both aldehyde- and ketone-derived proline enaminones are reported and discussed. Crystal structures of 10 proline enamines provide information on stereochemical aspects, i.e., double bond configuration and syn- vs. anti-positioning of the carboxylate relative to the enamine double bond. Furthermore, the obtained crystal structures are compared with the density functional theory-calculated structures of the ground and transition state and the postulated Seebach-Eschenmoser transition state.
منابع مشابه
Enamine-based organocatalysis with proline and diamines: the development of direct catalytic asymmetric Aldol, Mannich, Michael, and Diels-alder reactions.
Enamines and imines have long been recognized as key intermediates in enzyme catalysis, particularly within a class of enzymes organic chemists would very much like to emulate, the aldolases. Here we summarize the contributions of this laboratory to converting enzymatic enamines, and in some cases imines, into a versatile catalytic asymmetric strategy powered by small organic molecules.
متن کاملThe Structural Side of Conjugation in Some Stable Primary Enamines and Related Systems
Stable Conjugated Prim ary Enamines, ^-C onjugation , oand .T-Effects in Conjugated Systems The structures of l,6-diam ino-l,6-diphenyl-1.3,5-hexatriene (2) and its l,6-bis(N,N-bistrim ethylsilylam ino)-derivative (3) are com pared. The X-ray crystal structure analyses of 2 and 3 show that turning off the conjugation with the nitrogen lone pairs by orthogonal orientation of the R2N-plane has no...
متن کاملInvestigations on the formation of 4-aminobicyclo[2.2.2]-octanones.
Benzylidene acetone reacts with thiocyanates derived from secondary amines in a one-pot reaction to give 4-aminobicyclo[2.2.2]octan-2-ones. The reaction mixture was investigated for the presence of possible intermediates using GC-MS. These intermediates - diketones and enamines - were prepared and exposed to the same reaction conditions to examine the reaction mechanism. The reaction of ethyl s...
متن کاملSpongy Diamond
Rhombellanes are mathematical structures existing in various environments, in crystal or quasicrystal networks, or even in their homeomorphs, further possible becoming real molecules. Rhombellanes originate in the K2.3 complete bipartite graph, a tile found in the linear polymeric staffanes. In close analogy, a rod-like polymer derived from hexahydroxy-cyclohexane was imagined. Further, the ide...
متن کاملOn the Polymorphism of 12-Tungstoborate Heteropolyanion: Structure Determination and Its Functionalization with L-proline
A new structure related to previously reported structure of 12-tungstoborate Keggin-type polyoxometalate, K5[BW12O40], was synthesized and its characterization by single crystal X-ray diffraction shows the polymorph structure. Further attempts have been performed to provide three component compounds based on L-proline, lanthanoid cation and K5[BW12O40] (BW12 (II)) under hydrothermal conditions ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 107 48 شماره
صفحات -
تاریخ انتشار 2010