- A "bottom-up" approach to process development: Application of physicochemical properties of reaction products toward the development of direct-drop processes
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The "bottom-up" approach to development of direct-drop processes is a powerful, yet simple, strategy that every process chemist should consider for the development of efficient, cost-effective, and environmentally friendly processes. This approach is aided by a "parallel crystallization" technique, which allows for rapid identification of multiple solvent systems for the crystallization of the desired product using a minimal amount of material and solvent. This "bottom-up" approach is illustrated by several examples where the desired product is crystallized directly from the reaction mixture.
- Chen, Chien-Kuang,Singh, Ambarish K.
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- Nonionic radiographic contrast agents
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New nonionic radiographic contrast agents having the formula STR1 wherein Y is a single bond, --CH2 CH2 --, --CH2 O--, --OCH2 --, STR2 --CH2 --, --CH2 --CH2 --CH2 --,
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- Heterocyclic nonionic X-ray contrast agents V: A facile conversion of 2-tetrahydrofuroamides into α-hydroxy-δ-valerolactams and a general synthesis of lactams conjugated to 2,4,6-triiodoisophthalamides
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The synthesis of 2,4,6-triiodoisophthalamides substituted by a lactam moiety is described. A tandem ring opening-ring closure methodology consisting of a regiospecific ether cleavage of the tetrahydrofuroanilide 14b, followed by lactamization to α-oxygenated anilides 15b or 16b, gave α-O-functionalized-δ-valerolactams 12b or 13b, respectively. This approach is also compatible with the presence of ester and carbonyl chloride functions on the triiodophenyl moiety. A general synthesis of lactams 34-39 was also achieved. Further chemical modifications led to water soluble unsubstituted-lactams (34d, 35d, 37d) and α-hydroxyl-lactams [42(d,e), 13(d,e) and 43d] that are of interest as X-ray contrast agents.
- Marinelli,Arunachalam,Diamantidis,Emswiler,Fan,Neubeck,Pillai,Wagler,Chen,Natalie,Soundararajan,Ranganathan
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p. 11177 - 11214
(2007/10/03)
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- Process for preparation of 2-oxo-1 piperidinyl derivatives
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The process involves ring opening and ring closure of compounds containing a tetrahydrofuroyl group STR1 to provide facile synthesis of compounds containing a piperidin-2-one group of the formula STR2
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