Lewis Acid Catalyzed [3+2] Annulations of γ‐Butyrolactam‐Fused Donor–Acceptor Cyclopropanes with Aromatic Aldehydes and Aldimines

Abstract

A series of γ‐butyrolactam fused donor–acceptor (D–A) cyclopropanes were synthesized, and their reactivities in Lewis acid catalyzed [3+2] annulations with aromatic aldehydes and aldimines were studied. A range of γ‐butyrolactam fused tetrahydrofurans and γ‐butyrolactam fused pyrrolidines containing four contiguous stereogenic centers were generated in good‐to‐excellent yields and with exclusive diastereoselectivities and high enantiospecificity under the catalysis of 1 mol‐% of Al(OTf)3.

Donor–Acceptor Cyclopropane Ring Opening with 6-Amino-1,3-dimethyluracil and Its Use in Pyrimido[4,5-b]azepines Synthesis

“…dd, 2 J = 13.5 Hz, 3 J = 10.7 Hz, 1H, CH 2 ), 2.78 (br. dd, 2 J = 13.5 Hz, J = 5.5 Hz, 1H, CH 2 ). 13 C­{ 1 H} NMR (DMSO- d 6 , 126 MHz): δ 169.5 ( C O 2 Me), 169.4 ( C O 2 Me), 161.2 (C), 152.3 (2 × C), 152.2 (C), 150.8 (C), 139.7 (C), 135.9 (C), 105.4 (2 × CH), 86.4 (C), 59.9 (CH 3 O), 55.8 (2 × CH 3 O), 52.4 (CH 3 O), 52.2 (CH 3 O), 50.1 (CH), 38.5 (CH), 31.1 (CH 2 ), 30.0 (CH 3 N), 27.4 (CH 3 N).…”

“…The ease of synthesis, stability, and, at the same time, mild activation of multifaceted reactivity of donor–acceptor (DA) cyclopropanes in combination with high selectivity of most of their reactions make them valuable building blocks in organic synthesis. , Even common alkenes, reacting with DA cyclopropanes, can produce a set of different products depending on substituents in alkenes and cyclopropanes and the process conditions. Namely, these reactions afforded cyclopentane derivatives via formal [3 + 2]-cycloaddition, , indanes and tetralins by [3 + 2]- and [4 + 2]-annulations, respectively, or acyclic products through enol silyl ether alkylation/silyl group elimination …”

Synthesis of Heterocycles from Donor-Acceptor Cyclopropanes: A Five-Year Recap

“…In 2020, Yang and co-workers utilized -butyrolactam-fused DACs in the Lewis acid (Al(OTf) 3 ) catalyzed [3+2] annulations with aromatic aldehydes and aldimines to give -butyrolactam-fused tetrahydrofurans and pyrrolidines. 65 In 2020, Mikhaylov, Baranov, and co-workers used spiro(cyclopropane-1,4′-imidazole)-5′-ones 154, containing the imidazole-5-one an acceptor moiety, in a (3+2) cycloaddition to aldehydes in the presence of a Brønsted acid catalyst to give spiro(tetrahydrofuran-3,4′-imidazole)ones 156 and 157 (Scheme 32). 66 The reaction required the use of stoichiometric arenesulfonic acids and the products were isolated after neutralization with N,N,N′,N′-tetramethylguanidine (TMG) as a mixture of two diastereomers 156 and 157.…”

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

“…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).…”