Synthons intrinsic

Some subsequent discussion on compound 3 followed our original paper on this subject (N. Masciocchi, M. Bergamo, A. Sironi, Comments on the elusive crystal structure of 4-iodo-4 -nitrobiphenyl Chem. Comm, 1998,1347-1348 J. Hulliger, P. J. Langley, On intrinsic and extrinsic defect-forming mechanisms determining the disordered structure of 4-iodo-4 -nitrobi-phenyl Chem Comm, 1998, 2557-2558), but these papers, which describe the effects of small amounts of 4,4 -dinitrobiphenyl impurity in 3, only reinforce the idea of structures based on N02—I synthons. 

Pyrazole itself can be formed by the reaction of hydrazine with propargyl aldehyde. Using p-chloro-," P-alkoxy-" p-amino-" -enones as 1,3-dicarbonyl synthons are other ways to influence the regiochemistry of reaction." 2-(Dimethoxymethyl)-ketones react with arylhydrazines at the ketonic carbonyl, thus reversing the intrinsic reactivity of a p-keto-aldehyde." ... 

Deconstructing the Supra-Molecular Interactions in Bulk - Intrinsic Synthons... 

The lattice energy as a collection of inter-molecular interactions - intrinsic synthons aligned along specific crystallographic directions. 

The modem process chemist has at their disposal tools that allow a link to be made between the bulk crystal chemistry, the surface chemistry of the crystal faces and their potential interactions with solvents and impurities. Examples of industrial application include aspirin [58], the agrochemical product paclobutrazol [59]. The subsequent sections in this chapter provide the details of how such an understanding of the intrinsic and extrinsic synthons can be used in the design of pharmaceutical products in particular addressing the challenges in form selection, particle fonnation and formulation design. 

Lehn has outlined a hierarchical order of the terms tern-plating, self-assembly, and self-organization to describe the spontaneous formation of supramolecular assemblies composed of preprogrammed molecular components (i.e., tectons) Self-assembly concerns the antientropic aggregation of individual components to yield an ordered multi-molecular entity. Intermolecnlar interactions that are intrinsically preprogrammed (see synthon) into the bnilding... 

The allylation and crotylation of a-alkoxy aldehydes provide chiral 1,2-diol synthons which can be used in the synthesis of polyoj genated small molecules, for example, natural and unnatural sugars The tartrate-derived allylboronates I and 2 provide reagent-controlled selectivity in reaction with chiral glyceraldehyde acetonide 30. The intrinsic selectivity of the aldehyde is estimated by its reactions with pinacol allylboronates 33 and 34. The reagents 1 and 2 overcome the aldehyde s... 

Understanding of intermolecular interactions in molecular crystals in terms of synthons forms the basis of crystal engineering . Crystallization of organic compounds can lead to different forms of solids such as polymorphs, hydrates, solvates, salts, and co-crystals. These different forms of solid exhibit variable physico-chemical properties such as stability, crystal shape, compressibility, and density without changing its intrinsic chemical structure. In the pharmaceutical industry, these various solid forms of active pharmaceutical ingredients (APIs) can be used to improve physico-chemical properties and... 

---