Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• conditions, a porphyrin-based protocol for endoperoxidation of the diene, followed by the Kornblum–DeLaMare rearrangement and further telescoped transformations. This protocol yields different classes of products such as furans, tropone, diketones and hydroxyenones, all of them starting from the

• steps an electrochemical cyclization and an endoperoxidation photocatalyzed by TPP in an almost gram-scale (Scheme 38) [88]. In 2020, Burchill and George reported a 0.5 g-scale ene-reaction with singlet oxygen and a cromene derivative, thus giving a conjugated enone after a Kornblum–DeLaMare

• rearrangement (Scheme 39) [89]. Further photochemical [2 + 2] cycloaddition and hydrolysis allowed them to obtain rhodonoid A in 30% overall yield. Other similar natural products (rhodonoid B, E and F) were also prepared by the same synthetic strategy. Singlet oxygen has also been efficiently used for

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• related to rearrangements. Review 1 Named rearrangements of organic peroxides Rearrangements of organic peroxides are the key steps in many well-known processes such as the Baeyer–Villiger (BV), the Criegee and Hock reactions, the Kornblum–DeLaMare rearrangement, Dakin, and Elbs oxidation. The BV

• photochemical route developed for the synthesis of artemisinin the Hock rearrangement of hydroperoxide 223 selectively affords enol 224. This reactive intermediate 224 is then finally oxidized into artemisinin (Scheme 66) [334]. 1.4 Kornblum−DeLaMare rearrangement The Kornblum−DeLaMare rearrangement (KDLM) is a

• –DeLaMare rearrangement proceeds also on SiO2 [343]. The Kornblum–DeLaMare rearrangement is a convenient tool in organic chemistry for the conversion of monocyclic endoperoxides. These compounds are discussed in this review in the order of increasing ring size and the number of the starting substrates. The

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• has been prepared on a multigram scale. The previously assigned absolute configurations have been confirmed. The key steps of this synthesis are based on a modified version of the Kornblum–DeLaMare rearrangement, and on a highly regioselective and stereoselective ketone reduction with the MeCBS

• reagent. The taste evaluations indicate that none of these sesquiterpenes are sweet, instead the lippidulcine A is a cooling agent with a mint after taste. Keywords: ADH ketone reduction; cooling agent; Corey–Bakshi–Shibata reduction; dehydrogenation; hernandulcin; Kornblum–DeLaMare rearrangement

• amount of ketone 13 were isolated (Scheme 3). The latter is likely produced by a variant of the Kornblum–DeLaMare rearrangement [34][35] of the O-silyl precursor at room temperature, unfortunately 13 is very unstable. However, we envisaged the possibility of using this ketone, prior its tertiary alcohol