## 1 Introduction
Therefore, the objectives of this review paper are set in five directions as follows:  
* introduction of several chemical aspects related to privileged bicyclic structures containing \(O\)-atoms These frameworks are the very essential structural features found not only in the structure of viniferins, their semi-synthetic and synthetic derivatives, but also in a group of clinically approved drugs utilized to effectively treat various medical conditions. * in silico characterization of naturally occurring viniferins, their semi-synthetic and synthetic derivatives The pharmacologically promising molecules have to be evaluated in silico, in vitro, and in vivo using relevant approaches to provide a more detailed perspective on possible similarities between their desired characteristics and the properties of clinically approved drugs. Experimental estimation or calculation of these properties is absolutely vital for the pre-clinical and clinical evaluation of the compounds. Therefore, notable attention is paid to the calculation of various structural, physicochemical, PK, biochemical, and toxicological descriptors of viniferins and compounds synthesized on a viniferin structural platform. The eventual relationships between these in silico parameters are also investigated chemometrically. * indication of the advantages and limitations of the interactive tools employed The majority of the desired descriptors is generated via different free interactive tools accessible online. The purpose of the review paper is not only to highlight several advantages but also to present some shortcomings related to these applets. * focusing attention on the advantages and limitations of the analyzed naturally occurring viniferins, their semi-synthetic and synthetic derivativesFinally, the objective is also to outline the advantages and shortcomings of the considered compounds in light of the computed parameters and to guide possible further development and structural optimization. Some Types of Privileged Bicyclic Structures Present in the Structure of Clinically Approved Drugs and Viniferins  
The core (central) scaffold of a ligand, i.e., an endogenous or exogenous molecule (pharmacologically active compound, drug candidate, or drug) capable of interacting with required biological target(s), can be regarded as a privileged structure if the respective derivatives of this ligand can effectively interact with several biomolecule targets, for example, receptors, and show notably higher affinity and selectivity for these desired targets than other structures [36]. The general chemical structures of biologically active compounds of natural origin or semi-synthetic and synthetic agents containing a benzo[\(b\)]furan (**5**) core (previously known as a coumarone moiety, although this term is currently considered incorrect), bicyclic 2,3-dihydro benzo[\(b\)]furan (coumaran; **6**) structure and bioissosteric 1,3-dihydroobenzo[\(b\)]furan (phthallane; **7**) scaffold are provided in Figure 3.  
Particular bioissoteric modifications, as highly relevant strategies used in a drug discovery and development process, reflect the requirements to improve potency, optimize various structural and physicochemical properties, increase selectivity toward a desired biological target, reduce off-target effects, and improve toxicological characteristics of pharmacologically active agents [37, 38]. Bioissoteric replacement means the exchange of a 2,3-dihydrobenzo[\(b\)]furan (**6**) core for 1,3-dihydroobenzo[\(b\)]furan (**7**), for example. These scaffolds structurally differ from each other in the position of an \(O\)-atom within a five-membered ring as a part of a condensed bicyclic moiety. Heterocyclic systems with convenient size, steric, and stereochemical properties comprising \(O\)-atoms are present in naturally occurring molecules with very promising pharmacological activities, as viniferins show.