Throughout its history, the Brazilian Meeting on Organic Synthesis (BMOS) has accompanied the transformation of organic chemistry in Brazil and worldwide. The 20^th edition of the meeting, marking the ^44th anniversary of the first gathering of organic chemists in Brazil, could offer us an opportunity to revisit the history of what is the largest meeting devoted to Organic Synthesis in Brazil. However, this has been very well documented recently!¹ In addition, we, the editors, who received our academic training between the 2000s and the early 2010s, would be limiting ourselves to telling a story in the third person.

But writing a commemorative issue of the Journal of the Brazilian Chemical Society (JBCS) dedicated to BMOS means, in somehow, engaging with its history, which presents the first challenge: how to do so in the first person? We chose to reflect on the evolution of the field by examining the BMOS Special Issues in JBCS in 1996,² 1998,³ and 2001,⁴ alongside the 2026 edition. What changes have occurred in organic synthesis over the past decades? Among these many transformations, what core elements have endured?

Looking back at these Special Issues, a particularly interesting perspective emerges: they capture distinct moments in organic synthesis and offer a true snapshot of the field at those times. Given the short interval between the 1996 and 2001 Special Issues, we will treat these three issues as representative of the same period. In them, we find problems, strategies, and tools that remain relevant today, while other approaches have since been profoundly transformed.

Comparing these moments revealed a particularly significant feature: evolution does not occur by replacing old questions with new ones but by progressively expanding how we formulate and answer them.

For example, in 1996, the total synthesis of natural products was among the topics addressed. The synthetic target was often the ultimate goal, the Ithaka we were looking for. We should not forget that just two years earlier, in 1994, Holton et al.⁵ had stood out in the “race for Taxol”, in which research groups around the world competed to complete the first total synthesis of this potent chemotherapeutic agent and to solve the problem of its global supply. With the final product as the objective, yields at each reaction step naturally assumed a central role.

Many papers in these three Special Issues include terms such as enantio- and diastereoselective syntheses in their titles, reflecting the importance of stereochemical control and asymmetric induction. Total synthesis often served as the final proving ground where a methodology developed by one research group would be put to the test. Looking at this Special Issue, we find a paper that fits this description exactly: an enantioselective total synthesis using a methodology developed by the research group itself.

Curiously, however, a type of selectivity already described in 1996 was not yet part of our repertoire: chemoselectivity, that is, the transformation of one functional group in the presence of other functional groups that remain unchanged.⁶ This idea became more prominent with the development of late-stage functionalization, a process that selectively alters an already complex molecule.

Nowadays, with countless molecules needing to be synthesized and tested to bring a new drug to market, the time required to prepare a compound in the early stages of drug discovery can be as important as, or even more important than, the yield obtained in the synthesis. This Special Issue features a review article on late-stage C–H bond functionalization and a methodology for the late-stage introduction of trisubstituted imidazoles.

Since we are discussing the process of bringing a drug to market, this Special Issue also includes examples in which synthetic efficiency is central. One presents a concise synthesis of a chemotherapeutic agent, with microwaveassisted cyclization as the key step. Another combines a continuous-flow reaction with enzymatic kinetic resolution to synthesize an active pharmaceutical ingredient (API) intermediate.

In 1996, microwave-assisted reactions were already used in organic synthesis, but in recent years we have seen, worldwide, the emergence of enabling technologies as a distinct area of organic synthesis. This is also reflected in this Special Issue: some papers directly compare conventional heating techniques with microwave irradiation, while others address mechanochemistry and continuous-flow chemistry. These technologies arise not only to perform known transformations more efficiently but, in many cases, to enable transformations that would not be possible in any other way today.

Photocatalysis is another good example, but to discuss it, we need to go back in our own history. Radical reactions have been known for a long time and, for many years, were considered unpredictable and difficult to control, to the point that radical cyclization was not considered a key step in the total synthesis of a natural product until 1976, with the total synthesis of sativene and copacamphene by Bakuzis et al.⁷ here in Brazil.

In the 1996 and 1998 Special Issues, we find papers on radical additions. In both cases, the radicals were generated using tributyltin hydride as the initiator. In one paper, the corresponding author is known for naming one of the most important reactions in radical chemistry: the Giese reaction.

Radical chemistry appears again in this Special Issue, now accompanied by new tools for investigating and understanding its reactivity. One paper uses photocatalysis to study hydrogen atom transfer processes, combining experimental and theoretical approaches to elucidate the factors that govern them. Coincidentally, or perhaps not so coincidentally, the Giese reaction is used as proof of concept. This issue also presents a low-cost, modular photoreactor, validated across different transformations, as part of a proposal to make photochemistry more accessible to laboratories with limited resources.

The focus on efficiency, accessibility, and sustainability also appears in other current studies. Photochemistry, microwaves, continuous flow, and mechanochemistry for example, are integrated into a broader perspective on biomass valorization. Agro-industrial waste and renewable feedstocks are no longer merely alternative carbon sources; they are increasingly viewed as resources for producing higher-value compounds.

There is no doubt that enabling technologies are also related to sustainability. In 1996, Green Chemistry was emerging as a response to pollution prevention. Interestingly, the 12 Principles of Green Chemistry were not published until 1998! In this Special Issue, we find papers discussing more sustainable and greener syntheses.

In 1996, the term “organocatalysis” had not yet been introduced. It was officially coined only in 2000, when the work of MacMillan and co-workers,⁸ and List et al.⁹ helped consolidate and give enormous visibility to this new field. Notably, MacMillan spoke at the Itapema meeting in 2007 and at the Bento Gonçalves meeting in 2024. List also spoke at the Itapema meeting, and Barbas spoke at the Brasília BMOS in 2011. Did you attend any of these events, or perhaps all of them?

Regarding organocatalysis, this Special Issue features a paper that highlights how advances in the field are linked to new insights into catalyst mechanisms. It uses various spectroscopic and spectrometric methods to observe intermediates, shedding light on why certain catalyst structures outperform others.

This example points to a broader transformation: analytical tools have moved beyond merely detecting and confirming product structures and have become instruments for understanding the reaction itself. Nuclear magnetic resonance, for example, can reveal which species are actually present in the reaction medium and, therefore, which of them are in fact responsible for reactivity.

Organotellurium chemistry, for instance, was previously explored primarily through the transformations it could enable and in this Special Issue, this related chemistry is examined using advanced spectroscopic tools that allow the reactive species themselves to become the object of investigation.

This change also becomes apparent when we consider the goal of synthesis. In 1996, one of the papers sought to prepare new molecules with antithrombotic potential, using organic synthesis to obtain these substances and to test their biological activity. Nearly three decades later, this Special Issue brings together examples focused on developing new drug candidates, detecting chemical species, investigating photophysical and electrochemical properties, assessing biological activity, and valorizing renewable resources.

This integration goes even further when synthesis is connected to biological evaluation. Miniaturized platforms, automation, and direct screening strategies enable the preparation and testing of large numbers of compounds more rapidly and with less need for purification. Synthesis thus ceases to be an isolated step and becomes part of a continuous workflow for generating, evaluating, and selecting molecules.