33384-05-3Relevant academic research and scientific papers
Efficient heterogeneously palladium-catalysed synthesis of stilbenes and bibenzyls
Cusati, Giuseppe,Wedig, Anja,Djakovitch, Laurent
scheme or table, p. 77 - 81 (2010/04/23)
An alternative heterogeneously palladium catalysed procedure for the synthesis of functional stilbenes and bibenzyls is reported. Starting from aryl bromides and using simple commercially available Pd/C catalyst at a low catalytic rate (1 mol%), stilbenes are obtained with 30-100% GC-yields and bibenzyls are produced in a one-pot fashion with 27-100% GC-yields. The procedure showed, however, some limitations when applied to strongly deactivated aryl bromides that could be in some extent overcome by using corresponding iodo derivatives.
Correspondence between Molecular Functionality and Crystal Structures. Supramolecular Chemistry of a Family of Homologated Aminophenols
Vangala, Venu R.,Bhogala, Balakrishna R.,Dey, Archan,Desiraju, Gautam R.,Broder, Charlotte K.,Smith, Philip S.,Mondal, Raju,Howard, Judith A. K.,Wilson, Chick C.
, p. 14495 - 14509 (2007/10/03)
The crystal structures and packing features of a family of 13 aminophenols, or supraminols, are analyzed and correlated. These compounds are divided into three groups: (a) compounds 1-5 with methylene spacers of the general type HO-C6H4-(CH2)n- C6H 4-NH2 (n = 1 to 5) and both OH and NH2 in a para position; (b) compounds la, 2a, 2b, 2c, and 3a in which one or more of the methylene linkers in 1 to 3 are exchanged with an S-atom; and (c) compounds 2d, 1b, and 6a prepared with considerations of crystal engineering and where the crystal structures may be anticipated on the basis of structures 1-5, 1a, 2a, 2b, 2c, and 3a. These 13 aminols can be described in terms of three major supramolecular synthons based on hydrogen bonding between OH and NH2 groups: the tetrameric loop or square motif, the infinite N(H)O chain, and β-As sheet. These three synthons are not completely independent of each other but interrelate, with the structures tending toward the more stable β-As sheet in some cases. Compounds 1-5 show an alternation in melting points, and compounds with n = even exhibit systematically higher melting points compared to those with n = odd. The alternating melting points are reflected in, and explained by, the alternation in the crystal structures. The n = odd structures tend toward the β-As sheet as n increases and can be considered as a variable series whereas for n = even, the β-As sheet is invariably formed constituting a fixed series. Substitution of a methylene group by an isosteric S-atom may causes a change in the crystal structure. These observations are rationalized in terms of geometrical and chemical effects of the functional groups. This study shows that even for compounds with complex crystal structures the packing may be reasonably anticipated provided a sufficient number of examples are available.
