Exploring new dipeptides based on phenylglycine and Cα-methyl phenylglycine as hosts in inclusion resolutions
摘要:
Twelve homo-dipeptides derived from phenylglycine, Phg, and C-alpha-methyl phenylglycine, (alphaMe)Phg, were synthesized and tested as resolving agents in resolutions through selective crystallization of inclusion compounds. The 3D-structure of a hydrated (alphaMe)Phg dipeptide host was also solved by single crystal X-ray diffraction. These dipeptides were examined in the co-crystallization with 15 different racemic guests, mainly alcohols and sulfoxides. Next to confirming the literature results for the resolution Of methylphenylsulfoxide. a rather limited scope was found for new resolutions. Only racemic solketal could be resolved with H-(S)-(alphaMe)Phg-(S)-(alphaMe)Phg-OH in modest efficiency using various experimental techniques. This resolution was complicated by the formation of polymorphic host-guest crystals. Whereas a wide array of similar dipeptides could be explored as resolving agents, it is expected to be difficult to rationally design potentially Successful molecular structures. Compared to resolution by diastereomeric salt formation. inclusion complexes are less readily formed and therefore of a more limited scope and preparative applicability. (C) 2004 Elsevier Ltd. All rights reserved.
Exploring new dipeptides based on phenylglycine and Cα-methyl phenylglycine as hosts in inclusion resolutions
摘要:
Twelve homo-dipeptides derived from phenylglycine, Phg, and C-alpha-methyl phenylglycine, (alphaMe)Phg, were synthesized and tested as resolving agents in resolutions through selective crystallization of inclusion compounds. The 3D-structure of a hydrated (alphaMe)Phg dipeptide host was also solved by single crystal X-ray diffraction. These dipeptides were examined in the co-crystallization with 15 different racemic guests, mainly alcohols and sulfoxides. Next to confirming the literature results for the resolution Of methylphenylsulfoxide. a rather limited scope was found for new resolutions. Only racemic solketal could be resolved with H-(S)-(alphaMe)Phg-(S)-(alphaMe)Phg-OH in modest efficiency using various experimental techniques. This resolution was complicated by the formation of polymorphic host-guest crystals. Whereas a wide array of similar dipeptides could be explored as resolving agents, it is expected to be difficult to rationally design potentially Successful molecular structures. Compared to resolution by diastereomeric salt formation. inclusion complexes are less readily formed and therefore of a more limited scope and preparative applicability. (C) 2004 Elsevier Ltd. All rights reserved.
zed asymmetric SNAr reactions provide unique contribution to the catalyticasymmetric α‐arylations of carbonyl compounds to produce biologically active α‐aryl carbonyl compounds, the electrophiles were limited to arenes bearing strong electron‐withdrawing groups, such as a nitro group. To overcome this limitation, we examined the asymmetric SNAr reactions of α‐amino acid derivatives with arene chromium
尽管相转移催化的不对称S N Ar反应为羰基化合物的催化不对称α-芳基化反应产生了生物活性的α-芳基羰基化合物做出了独特贡献,但亲电试剂仅限于带有强吸电子基团的芳烃,例如硝基。为了克服这一局限性,我们研究了α-氨基酸衍生物与衍生自氟代芳烃的芳烃铬配合物(包括含给电子取代基的芳烃铬配合物)的不对称S N Ar反应。联萘改性的手性相转移催化剂可有效地促进芳基化反应,从而生成相应的α,α-二取代的α-氨基酸,其中包含具有高对映选择性的各种芳族取代基。
Exploring new dipeptides based on phenylglycine and Cα-methyl phenylglycine as hosts in inclusion resolutions
Twelve homo-dipeptides derived from phenylglycine, Phg, and C-alpha-methyl phenylglycine, (alphaMe)Phg, were synthesized and tested as resolving agents in resolutions through selective crystallization of inclusion compounds. The 3D-structure of a hydrated (alphaMe)Phg dipeptide host was also solved by single crystal X-ray diffraction. These dipeptides were examined in the co-crystallization with 15 different racemic guests, mainly alcohols and sulfoxides. Next to confirming the literature results for the resolution Of methylphenylsulfoxide. a rather limited scope was found for new resolutions. Only racemic solketal could be resolved with H-(S)-(alphaMe)Phg-(S)-(alphaMe)Phg-OH in modest efficiency using various experimental techniques. This resolution was complicated by the formation of polymorphic host-guest crystals. Whereas a wide array of similar dipeptides could be explored as resolving agents, it is expected to be difficult to rationally design potentially Successful molecular structures. Compared to resolution by diastereomeric salt formation. inclusion complexes are less readily formed and therefore of a more limited scope and preparative applicability. (C) 2004 Elsevier Ltd. All rights reserved.