**1. Introduction**

Among unnatural α-amino acids, α,α-disubstituted amino acids are key biological scaffolds with many specific roles and properties that have made them increasingly attractive in the fields of organic chemistry, biochemical research and drug discovery [1–3]. They have unique structural properties, which make them ideal candidates to be included in the design of new pharmaceutically active compounds, as well as intermediates for the study of pathological pathways [4–6].

Synthetic approaches for the synthesis of di- or trisubstituted nitroalkenes, valuable intermediates for the synthesis of α,α-disubstituted amino acids, are abundant in the literature, but there are very scarce data reporting synthetic routes for tetrasubstituted nitroalkenes [7,8]. Herein we describe a reproducible methodology for the synthesis of these compounds (Figure 1) that started from easily available ketones (**1**), which are converted to tetrasubstituted nitroolefins (**3**), by reaction of an acrylate intermediate (**2**), with an appropriate nitration reagent. Nitroalkenes will be organocatalytically reduced to afford enantioenriched nitroalkanes (**4**), highly functionalized chiral starting materials for further transformations (Figure 1).

**Citation:** González, P.C.; Rossi, S.; Sanz, M.; Vasile, F.; Benaglia, M. Synthesis of Tetrasubstituted Nitroalkenes and Preliminary Studies of Their Enantioselective Organocatalytic Reduction. *Molecules* **2023**, *28*, 3156. https://doi.org/ 10.3390/molecules28073156

Academic Editor: Renata Riva

Received: 26 February 2023 Revised: 28 March 2023 Accepted: 29 March 2023 Published: 1 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Figure 1.** Synthetic approach for the synthesis of tetrasubstituted nitroalkenes and their enantioselective catalytic reduction.
