# Approaches to the Functionalization of Organosilicon Dendrones Based on Limonene
## 1 Introduction  
Dendrimers are widely used currently due to their unique structure. In terms of structure, they can be considered as more ordered analogues of branched polymers with a similar chemical structure of the polymer chain. However, due to their mathematically precise molecular geometry, dendrimers differ significantly from their polymer analogs. Since the structure and the number of generations determine the molecular weight, dendrimers exhibit no statistical distribution of molecular weights, in contrast to the polymer analogs. Due to the growth of the dendrimer density from the center to the periphery, such molecules at higher generations become impenetrable spheres and behave as colloidal particles. Nevertheless, these molecules contain cavities for which the size and geometry can be controlled by the chemical structure of the branches and the branching center. Owing to this, dendrimer molecules are used in various fields, for example, in the delivery of drugs and genetic materials [1; 2], to transport catalysts and produce nanoparticles [3; 4; 5; 6; 7; 8], and in nonlinear optics devices [9; 10; 11; 12; 13]. Conjugated star-shaped molecules with donor-acceptor links are used as donor components in organic photovoltaic cells [14; 15; 16]. Functional dendrimers are now widely used in materials science, nanotechnologies, and to modify the physical chemistry of a surface; in particular, in chromatography as a stationary phase [17], for selective sorption [18; 19] and for the preparation of organic-inorganic nanocomposites [20], inorganic nanomaterials [21], mesoporous coatings. and nanoparticles [22; 23].  
Carbosilane dendrimers (CDs) are one of the interesting and promising classes of dendritic molecules. Due to their chemical structure, primarily the high Si-C bond energy, these molecules possess high biological inertness and biological compatibility, high thermal and thermal-oxidative stability, and high hydrophobicity [24; 25]. Due to these properties,this type of macromolecules are employed in many areas of today's science; however, they make the largest contribution to catalysis [26; 27; 28] and drug delivery [29; 30; 31; 32; 33; 34].  
For the synthesis of these compounds, approaches to the preparation of CDs have been developed by teams guided by [PERSON] [35; 36; 37] and [PERSON] [38; 39]. However, although proven techniques exist, new approaches to the synthesis of carbosilane, carbosilane-siloxane, and other hybrid dendrimers are currently under development. This activity is primarily driven by the need to simplify the synthesis, obtain new functional macromolecules, and obtain hybrid dendrimers [40; 41].  
We have shown in our previous studies that natural terpen can be used to obtain block copolymers [42; 43] and dendrimers [44]. This approach is based on the phenomenon of regioselective hydrosilylation of the isoprenyl double bond, while the cyclohexene double bond can be involved either in subsequent hydrothiolation or in further functionalization. In this way, based on limonene, carbosilane, and carbosilane-siloxane dendrons of various generations in which limonene is the branching point were obtained. The presence of a cyclohexene double bond in such dendrons allows further functionalizations to be implemented.  
The purpose of this study is to show that functional groups can be incorporated at the cyclohexene double bond and that limonene-based dendron chains can be functionalized by simple synthetic methods to obtain macromolecules with various structures, including hybrid dendrimers, Janus dendrimers, and macroinitiators.