Ketenedithioacetals as Surrogates for the Formal Insertion of Ketenes into Donor–Acceptor Cyclopropanes

Abstract

The reactivity of donor-acceptor (D-A) cyclopropanes towards acceptor-substituted ketenedithioacetals was investigated. In a Lewis-acid-catalyzed (3+2)-cycloaddition, the corresponding dithiaspiro compounds were synthesized in

Cyclopentene Synthesis by a Catalytic [3+2] Annulation of Donor‐Acceptor Cyclopropanes with Polarized Alkenes

“…As part of our ongoing interest in this field, we here report a Sc(OTf) 3 ‐catalyzed [3+2] annulation of donor‐acceptor cyclopropanes with acyclic α‐oxo ketene dithioacetals, which affords a series of highly substituted cyclopentenes (Scheme d). Very recently, Werz and coworkers reported a formal insertion of ketene into DA‐cyclopropanes to prepare cyclopentones, in which α‐benzoyl ketene cyclic dithioacetal was used as a ketene equivalent …”

Exploiting Heavier Organochalcogen Compounds in Donor–Acceptor Cyclopropane Chemistry

“…Interestingly, a strong keto−enol tautomerism was observed by additional NMR spectroscopy experiments (Scheme 18). 38 In 2019, the group of Guo made use of thiourea (51) as a cheap, odorless, and bench stable thiocarbonyl source to generate 2-amino-4,5-dihydrothiophene derivatives 53 via a (3 + 2) annulation process with various D−A cyclopropanes. Conducted control experiments corroborate a (3 + 2)cycloaddition/deamination/decarboxylation sequence, where-by thiourea plays a 3-fold crucial role as 2π component (CS) coupling partner, amine source and decarboxylation reagent.…”

Synthesis of (Het)aryl 2-(2-hydroxyaryl)cyclopropyl Ketones

“…Coupling constants (J) are in Hertz. 19 F NMR spectra were recorded at 471 MHz with fluorobenzene as an external reference (δ = −113.1 in DMSO-d6). Infrared spectra were recorded on an FTIR spectrometer ALPHA II (Bruker, Billerica, MA, USA) in KBr for solid substances and in nujol for oils.…”

“…During last decades donor-acceptor (D-A) cyclopropanes [1][2][3][4][5][6] attracted a significant attention of organic chemists due to the excellent combination of their availability and high reactivity toward diverse classes of reaction partners: nucleophiles [4,[7][8][9][10], electrophiles [11,12], radicals [13,14], dipolarophiles [15][16][17][18][19][20][21][22], dipoles [23][24][25], 1,3-dienes [26][27][28], etc. (Scheme 1a).…”

“…19 F NMR (DMSO-d 6 , 471 MHz) δ= −125.3. IR (cm −1 ) 3355, 3085, 1640, 1510, 1440, 1365, 1270, 1230, 1180, 1015, 810, 770, 715.…”