Synthesis of silacyclopent-2-en-4-ols via intramolecular [2 + 2] photocycloaddition of benzoyl(allyl)silanes

Abstract

Organosilicon compounds are versatile units with a wide range of uses from medicinal chemistry to the field of organic electronics.

Recent progress and perspectives in photo-induced organic reactions of acylsilanes

“…In 2019, the Afonso and Candeias group reported a unique synthesis of silacyclopentanols using cinnamyl silane substrates 1m , in which the cyclization mode mimics the UV-initiated Paternò–Büchi type [2 + 2] cycloaddition (Scheme 19). 37 It is noteworthy that light irradiation did not initiate the formation of highly reactive siloxycarbenes. Instead, CO activation occurred selectively, enabling [2 + 2] cycloaddition upon reaction with alkenes.…”

Mechanisms and Synthetic Strategies in Visible Light‐Driven [2+2]‐Heterocycloadditions

“…In 2019, Candelais et al. reported an intramolecular PB reaction using 419 nm light in which the carbonyl part is an acylsilane 55 [46] . The bicyclic product 56 was observed by NMR, but was unstable to silica gel column chromatography, yielding the silylacycle 57 together with other by‐products.…”

“…In 2019, Candelais et al reported an intramolecular PB reaction using 419 nm light in which the carbonyl part is an acylsilane 55. [46] The bicyclic product 56 was observed by NMR, but was unstable to silica gel column chromatography, yielding the silylacycle 57 together with other by-products. By treatment with a 10 % NaHSO 4 aqueous solution, the authors could convert quantitatively and selectively 56 to the silylacyclopentene 57, triggering the formation of different five-membered silylacycles (Scheme 11).…”

Functionalized Cyclopentenes via the Formal [4+1] Cycloaddition of Photogenerated Siloxycarbenes from Acyl Silanes

“…Following the general procedure, 3a was obtained in 66% yield (29.5 mg) as an off-white amorphous solid. 23 (8). Cyclopentene 3b (20 mg, 40 μmol) was dissolved in dry ACN (2 mL) in an oven-dried round-bottom flask under an argon atmosphere.…”

“…Activated alkynes have been shown to undergo slow inter- and intramolecular cyclopropenations following ring collapse to give β-silylated enones (Scheme ), , while ambiphilic donor–acceptor carbenes derived from trifluoroacetylsilanes were recently explored. , Concerning olefins, only the highly electron-withdrawing dialkyl fumarate and maleate have been reported to undergo cyclopropanation, , yielding cyclopropyl silyl ethers that are prone to ring opening through hydrolysis and are therefore not synthetically useful for cyclopropane synthesis. Despite the preference for acylsilane carbonyl to react in a [2+2]-photocycloaddition reaction, , singlet nucleophilic carbenes with tethered olefins were recently shown to undergo rapid [2+1]-cycloaddition . All in all, formal cyclopropanation of olefins with acylsilane-derived carbenes remains poorly explored due to the required presence of electron-withdrawing groups in the olefin which renders instability to the resulting silyl ether cyclopropanes.…”