Methodological development using diazoketones aiming at the synthesis of bicyclic rings: aromatic ketones and naphthols

Author(s)

Evandro de Azevedo Rocha

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2021-09-15

Examining board members

Antonio Carlos Bender Burtoloso; Isac George Rosset

• Advisor: Antonio Carlos Bender Burtoloso

Abstract

Diazoketones and β-ketosulfoxonium ylides are quite versatile synthetic precursors and may undergo sundry variations, such as Wolff\'s photochemical rearrangement,whom the ability to form nuclear ketone intermediates that can form adutes cycles. Thus, the first part of this work is the development of a methodology for the use of Rearrangements Wolff in α- diazoketones in order to prepare aromatic bicyclic ketones. These diazoketones were prepared from their carboxylic effects through the diazometane acylation methodology already described in the literature, obtaining ten previous examples, with sundry variation of 72-87%. In the photochemical study, to find the best reactive condition to get a bicycle, the diazoketone would be used that would lead to a 5 membered ring formation, as a formation would be seriously favored by entropic and enthalpy factors, as well as nineteen diazoketones, already synthesized were subjected to the Wolff rearrangement, where some examples were recorded after the formation of bicyclic aromatic ketones with ranging from 38 to 44%. Since this initial demonstrative study is effective, it was possible to study the intramolecular cycling variations in bicycle ring size (ranging from 4 to 7 members) and the influence on the aromatic ring donor group reactivity in ortho, meta and para positions in relation to the diazo substituent group, in addition to verifying the influence of different donor groups on the aromatic ring, where it was found that a group of donors, even if weak, requires the position of the diazoketone chain target to occur the formation of the bicyclic aromatic ketone and that this reaction is shown to be regiselective to the detriment of the formation of a single regioisomer (ortho cyclization). The second part of this work consisted of the application of , α, β-unsaturated diazoketones as building blocks in the synthesis of naphthols. This class of diazoketones was prepared by reacting diphenylphosphite with benzyl bromine acetate followed by 3 steps for the formation of diazophosphonate. The diazophosphonate was subjected to the Horner-Wadsworth-Emmons olefin reaction with benzaldehyde to form , α, β- unsaturated diazoketone of Z geometry with a yield of 53%. This diazoketone was used in an initial study involving the catalyst Rh2(OAc)4, which, through a cyclization reaction, led to the formation of the naphthol nucleus of interest. (AU)

• FAPESP's process: 18/03667-0 - Development of a new methodologies for synthesis of bicyclic aromatic ketones and naphthols employing diazoketones and Beta-keto sulfoxonium ylides
• Grantee: Evandro de Azevedo Rocha
• Support Opportunities: Scholarships in Brazil - Master