Regioselective Photooxidation of Citronellol: A Way to Monomers for Functionalized Bio-Polyesters

Abstract

Dye-sensitized photooxygenation reaction of bio-based double bond-containing substrates is proposed as sustainable functionalization of terpenes and terpenoids to transform them into polyoxygenated compounds to be employed for the synthesis of new bio-based polyesters. As proof of concept, citronellol 1 has been regioselectively converted into diol 4 using singlet oxygen (1 O 2), a traceless reagent that can be generated from air, visible light and zeolite supported-photosensitizer (Thionine-NaY). With our synthetic approach, diol 4 has been obtained in two-steps, with good regioselectivity, using green reagents such as light and air, and finally a solvent-free oxidation step. From this compound, a citronellol-based copolyester of poly(butylene succinate) (PBS) has been synthesized and fully characterized. The results obtained evidence that the proposed copolymerization of PBS with the citronellol-based building blocks allows to obtain a more flexible and functionalizable material, by exploiting a largely available natural molecule modified through a green synthetic path.

Synthesis of symmetric bis-α-ketoamides from renewable starting materials and comparative study of their nucleating efficiency in PLLA

“…N,N'-(Ethane- (12), 43 (16), 44 (13), 45 (8.0), 46 (15), 54 (6.5), 56 (7.6), 58 (72), 59 (68), 70 (18), 71 (8.3), 72 (19), 73 (30), 81 (6.0), 86 (27), 87 (7.6), 98 (18), 99 (100), 100 (6.7) (12), 41 (37), 42 (14), 43 (14), 44 (28), 45 (5.4), 46 (44), 54 (5.9), 55 (17), 56 (16), 58 (100), 59 (71), 60 (5.4), 67 (11), 69 (27), 70 (9.4), 72 (80), 73 (35), 82 (22), 83 (6.5), 84 (8.9), 86 (50), 87 (13), 98 (8.4), 99 (7.5), 100 (66), 101 (20), 114 (74), 115 (13), 116 (5.7), 126 (16) General procedure for the synthesis of compounds 1a-g…”

“…28 While MCRs have been widely exploited in medicinal chemistry, [29][30][31] their use in other elds is still limited. 32,33 Building on our experience in the development of new synthetic methodologies using MCRs, [33][34][35][36] following our recent interest in the eld of biopolymers, 37 and inspired by the potential of the combination of MCRs with the use of renewable starting materials derived from biomass, 35,[38][39][40] we have planned to synthesize the symmetric bis-ketoamides 1 through an easy modulable multicomponent approach (Fig. 1).…”

Oxidation of Monoterpenes to Form Diols and Triols: A Versatile Toolbox for Polymer Synthesis

“…[18] Lanteri et al have also reported recent methods for producing citronellolbased diols via photooxidation and reduction, which were shown to readily produce co-polyesters by polycondensation. [46] In this work, we further expanded upon the variety of terpenes that can undergo these robust, well-established oxidations including cyclic, acyclic, oxygenated, and chiral starting materials. However, we aimed at the production of a series of terpene-derived diols and triols using mild reaction conditions, which produce environmentally benign by-products.…”

Photooxidation of 2-(tert-Butyl)-3-Methyl-2,3,5,6,7,8-Hexahydroquinazolin-4(1H)-one, an Example of Singlet Oxygen ene Reaction

“…Herein we report a hydroperoxidated product (12) by a spontaneous photooxidation where hexahydroquinazolinone (11) is crystallized by overnight diffusion in an n-hexane/CH 2 Cl 2 (80:20) solvent mixture, Scheme 1. The scheme makes use of oxygen in the environment and at the same time is able to avoid the use of photosensitizers (metallic catalysts or natural colorants), which is a constant challenge [14,15].…”

“…Molecules 2020, 25, x FOR PEER REVIEW 2 of 16 solvent mixture, Scheme 1. The scheme makes use of oxygen in the environment and at the same time is able to avoid the use of photosensitizers (metallic catalysts or natural colorants), which is a constant challenge [14,15].…”