Preparation of aromatic geraniol analogues via a Cu(I)-mediated Grignard coupling

Abstract

Terpenos alílicos difuncionais constituem-se em importantes blocos de construção sintéticos. A funcionalização de derivados geranílicos protegidos por SeO 2 /t-BuO 2 H adsorvido em SiO 2 , propicia uma rota conveniente para tais compostos. Os grupos protetores escolhidos efetivamente influenciam o processo de oxidação. Também, desenvolveu-se uma eficiente síntese de derivados 2-geranilfenóis através de um acoplamento de Grignard mediado por Cu(I) entre derivados de 2-lítiofenóis e substratos geranílicos.Difunctional allylic terpenes are important synthetic building blocks. Functionalization of protected geranyl derivatives by SeO 2 /t-BuO 2 H adsorbed on SiO 2 provides a convenient route to such compounds. The chosen protecting groups clearly influence the oxidation process. Also, an efficient synthesis of 2-geranylphenol derivatives via a Cu(I)-mediated Grignard coupling of 2-lithiophenols and geranyl substrates was developed.

Essential Oils as a Sustainable Raw Material for the Preparation of Products with Higher Value-Added

“…Paz e colaboradores realizaram a oxidação seletiva de grupos metil-alílicos presentes em derivados de geraniol 24, utilizando SeO 2 /SiO 2 (10% m/m) como suporte sólido e t-BuO 2 H. 70 A reação permitiu a obtenção de uma mistura de produtos contendo 75 % do álcool trans-α,β-insaturado 25 e 25 % do aldeído trans-α,β-insaturado 26. A mistura de produtos foi submetida à redução com NaBH 4 em etanol, resultando apenas na formação do álcool alílico correspondente, com 75 % de rendimento (Esquema 15).…”

Rapid Method of Friedel-Crafts Alkylation of Phloroglucinol by Microwave in Dry Media and Reusable Catalyst

“…Their structural complexity when phloroglucinol is alkylated draws attention; because in general, it is a challenge to attempt to incorporate nonpolar chains in a tri-substituted aromatic ring with OH groups (electron donating group).Among the most common synthetic strategies reported for the introduction of nonpolar chains in an aromatic ring (C-Alkylation) are: Friedel-Crafts reactions, Michael addition and multistep processes consisting of a neutral-pathway leading to the early O-alkylation, followed by a series of ionic rearrangements resulting finally in C-alkylations. 9 There are many publications that report different methods for accomplishing these coupling reactions in the synthesis of prenyl phenols and geranylphenols 8,[10][11][12] , most with low yields and using highly toxic homogeneous and heterogeneous (solid) catalysts such as HF, H 2 SO 4 , AlCl 3 , or BF 3 13,14 . But there are no reports of Friedel-Crafts allylation of the phloroglucinol molecule, via microwave mediated Electrophilic Aromatic Substitution (EAS).…”

An Efficient Procedure Based on a MW-Assisted Horner–Wadsworth-Emmons Reaction for the Synthesis of (Z)-3,3-Trisubstituted-a,b-unsaturated Esters

“…3,3-Trisubstituted α,β-unsaturated methyl esters 1 were identified as valuable synthetic intermediates to achieve, after simple synthetic elaborations, the desired chemical diversity of the library ( Scheme 1 ). It has to be outlined that the allylic oxidation step of the proposed synthetic pathway ( Scheme 1 , step C) is selective toward α,β-unsaturated esters with ( Z )-configuration [ 2 ]. Accordingly, our principal aim was to come up with a rapid and economic synthetic plan for the preparation of ( Z )-3,3-trisubstituted-α,β-unsaturated methyl esters in amounts suitable for their subsequent derivatization and for preparing the whole compound library.…”