Weak C-H…O hydrogen bonds in alkaloids: An overview

Abstract

An overview of general classification scheme, medicinal importance and crystal structure analysis with emphasis on the role of hydrogen bonding in some alkaloids is presented in this paper. The article is based on a general kind of survey while crystallographic analysis and role of hydrogen bonding are limited to only those alkaloids whose three-dimensional structure has been reported by us. The C-H…O hydrogen bonding in the solid state in alkaloids has been found to be predominant and this observation makes the role of hydrogen bonding in organic molecular assemblies very important.

6,7,8,9,10,11-Hexahydro-13H-azocino[2,1-b]quinazolin-13-one

“…In the crystal structure of the title compound weak intermolecular C-H•••X hydrogen bonds are observed as it is often the case in alkaloids (Rajnikant et al, 2005) Fig. 2 and 3; for numerical values and symmetry operators see Table 1).…”

“…For cyclooctene ring conformations, see: Barnes et al (1992). For weak hydrogen bonds in alkaloids, see: Rajnikant et al (2005).…”

9-Furfurylidene-2,3-dimethyl-6,7,8,9-tetrahydro-4H-thieno[2′,3′:4,5]pyrimidino[1,2-a]pyridin-4-one

“…In the crystal structure of the title compound weak intermolecular C-H•••X hydrogen bonds (Table 1) are observed as it is often the case in alkaloids (Rajnikant et al, 2005)…”

“…For the physiological activity of thieno[2,3-d]pyrimidin-4-ones and their derivatives, see: Kapustina et al (1992); Blaskiewich et al (1975); Wä hä la et al (2005); Lilienkampf et al (2007); Han et al (2007); Moore et al (2006). For weak hydrogen bonds in alkaloids, see: Rajnikant et al (2005). For bond-length data, see: Allen et al (1987).…”