Cyclopropanation with Fischer Acyloxycarbene Complexes:  Preparation of Cyclopropane and Cycloheptane-Fused γ-Lactones

Abstract

[reaction: see text] A sequential acylation-intramolecular cyclopropanation reaction takes place upon treatment of a series of tetraalkylammonium acylchromates with beta,gamma-unsaturated acyl chlorides at -10 degrees C. The reaction leads to 2-oxabicyclo[3.1.0]hexan-3-ones with exo selectivity in good yields. The diastereoselectivity of the reaction allows the preparation of cis-divinyl cyclopropanes, which evolve via Cope sigmatropic reaction toward cycloheptadiene derivatives. Furthermore, the aromatic Cope rearrangement of a series of cis-aryl vinyl cyclopropanes prepared by means of this methodology has been studied.

New Benzenoid Derivatives and Other Constituents from Lawsonia inermis with Inhibitory Activity against NO Production

“…The 1 H-NMR spectrum of 1 showed the presence of four mutually coupling aromatic protons [δ 7.46 (1H, br t, J = 7.8 Hz, H-8), 7.60 (1H, br t, J = 7.8 Hz, H-9), 7.85 (1H, br d, J = 7.8 Hz, H-7), 8.55 (1H, br d, J = 7.8 Hz, H-10)], four mutually coupling methylene protons [δ 2.79 (1H, m, H-4α), 2.95 (1H, m, H-4β), and 3.07 (2H, m, H-5)], and an oxymethine proton [δ 6.07 (1H, s, H-1)], and a hydroxyl group [δ 3.88 (1H, br s, D 2 O exchangeable, OH-1)]. The 1 H-NMR spectrum of 1 was similar to 3,4,5,6-tetrahydro-8-methoxy-2 H -benzo[ 6 , 7 ] cyclohepta[ b ]furan-2-one ( 1a ) [ 7 ], except that H-8, α-hydroxy-γ-butyrolactone moiety at C-3a and C-10b, and a ketone at C-6 of 1 replaced OMe-8, γ-butyrolactone moiety at C-3a and C-10b, and H-6 of 1a [ 7 ]. This was supported by (1) NOESY correlations observed between H-1 (δ H 6.07)/H-10 (δ H 8.55), H-8 (δ H 7.46)/H-7 (δ H 7.85), and H-8 (δ H 7.46)/H-9 (δ H 7.60), and (2) HMBC correlations observed between H-1 (δ H 6.07)/C-2 (δ C 169.1), H-1 (δ H 6.07)/C-10a (δ C 127.2), H-4 (δ H 2.79, 2.95)/C-6 (δ C 201.0), H-8 (δ H 7.46)/C-6a (δ C 138.9), and H-8 (δ H 7.46)/C-10 (δ C 128.9).…”

The chemistry of the carbon–transition metal double and triple bond: annual survey covering the year 2002

“…270, Scheme 22) was reported [470]. Cyclopropanation was observed when chromium carbene acylates were treated with ␤,␥-unsaturated acid chlorides [471]. Formation of the acyloxycarbene complex (e.g.…”

Synthesis of fused tricyclic systems by thermal Cope rearrangement of furan-substituted vinyl cyclopropanes

“…There are just three examples of the thermal Cope rearrangement of 1-furanyl-2-vinylcyclopropanes. 11,12 In 1980, Maas and Hummel described the rearrangement of the very simple substrates 13a and 13b to give the 3a,7-dihydro-4Hcyclohepta[b]furans 14a and 14b in low yield by heating them in toluene or deuterated benzene (Scheme 4). 11 Aromatized 7,8-dihydro-4H-cyclohepta[b]furans 15a and 15b were obtained when toluene solutions of the substrates were heated at higher temperatures in a sealed tube.…”

“…The only other example of the reaction is an unusual one published by Barluenga and coworkers, in which the unstable fused tricyclic lactone 17 was prepared by thermal rearrangement of the lactone-containing vinyl cyclopropane 16 at 85°C. 12 A systematic study of the scope of the thermal Cope rearrangement of 1-furanyl-2-vinylcyclopropanes has not been published and there are no examples of the use of the reaction to prepare more complex fused polycyclic systems from cyclopropyl-substituted furans that possess additional rings.…”