The following discussion will assume a simple case, where there is only one stereocenter
and two mirror-image isomers.
can be either R or S configuration, and hence, the possible combinations are RRRR, RRSS, RRRS, RRSR, SSRR, SSSS, SSRS, SSSR, RSRR, RSSS, RSRS, RSSR, SRRR, SRSS, SRRS, and SRSR configurations.
The caffeine molecule lacks a stereocenter
and thus has no rotational isomers whatsoever.
Naringenin is the aglycone of the flavonoid glycoside naringin, a chiral natural product, usually with an S-configuration at the stereocenter
The reaction also includes the facet of stereocenter
control through the use of either L- or D- proline to give either the S or the R version of the product, respectively.
The compound 2 has two (adjacent) stereocenters
giving rise to two multiplets (2H) at 4.
Babu, "Direct lactonization of a-amino [gamma], [delta]-unsaturated carboxylic acid esters via olefin activation: stereo- and regioselective production of homoserine lactone scaffolds having contiguous stereocenters
," Tetrahedron, vol.
In the key desymmetrisation step the morphan core of the alkaloids will be constructed and the configuration of 3 of their 4 stereocenters
will be established.
The synthesis of these natural components entails an increased financial burden because of their complex structures, sometimes, of multiple stereocenters
The synthesis of 1 started from an anti-selective asymmetric aldol reaction (37) between silyl enol ether 2 and aldehyde 3 to set the two stereocenters
at C4 and C5 of 4 (Fig.
They have arranged the papers into five sections dealing with the creation of new stereocenters
using existing stereochemical information in the molecule or from a chiral auxiliary, metal-catalyzed asymmetric synthesis, asymmetric catalysis with enzymes and small organic molecules, asymmetric reactions in total synthesis, and asymmetric synthesis for the production of drugs and fine chemicals.
We proposed the preparation of a novel and diverse library of conformationally constrained peptidomimetics containing quaternary stereocenters
derived from B/C/P approach with increased biological relevance.