Reaction of Hetareno[ e ]pyrrolediones with 1,3-C,N-Binucleophiles. Isolation of Intermediate Product of Spiro Heterocyc
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Reaction of Hetareno[e]pyrrolediones with 1,3-C,N-Binucleophiles. Isolation of Intermediate Product of Spiro Heterocyclization A. I. Kobeleva, M. V. Dmitrieva, and A. N. Maslivetsa,* a
Perm State University, Perm, 614990 Russia *e-mail: [email protected]
Received February 14, 2020; revised March 26, 2020; accepted March 28, 2020
Abstract—Ethyl 1,2,4-trioxo-2,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylates reacted with ethyl (2Z)-[2-oxo-2H-1,4-benzoxazin-3(4H)-ylidene]acetates to give ethyl 3a-[2-ethoxy-2-oxo-1-(2-oxo-2H1,4-benzoxazin-3-yl)ethyl]-2-hydroxy-1,4-dioxo-3a,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylates. The product structure was confirmed by X-ray analysis. Keywords: spiro heterocyclization,1,3-C,N-binucleophiles, benzoxazinones, hetareno[e]pyrrole-2,3-diones, ethyl 1,2,4-trioxo-2,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylates, X-ray analysis, enamines
DOI: 10.1134/S1070428020070301 Spiro heterocyclization of hetareno[e]pyrrole-2,3diones, e.g., pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones) by the action of 1,3-C,N-binucleophiles such as enamines involves successive addition of the β-CH group of enamine to the C3a atom of pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-trione, followed by intramolecular attack of the amino group of the enamine fragment on the C4=O lactone carbonyl group and cleavage of the C4–O5 bond of the benzoxazine fragment, to produce substituted 1,7-diazaspiro[4.4]nonadiene derivatives [1–13]. In some cases, the spiro heterocyclization products undergo further transformations [14–17]. However, in no case did we succeed in isolating primary addition products of enamines to C3a of hetareno[e]pyrrolediones.
By reacting ethyl 1,2,4-trioxo-2,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylates 1a and 1b with ethyl (2Z)-[2-oxo-2H-1,4-benzoxazin-3(4H)ylidene]acetates 2a and 2b (enamines) in anhydrous ethyl acetate at room temperature (24 h) we obtained ethyl 3a-[2-ethoxy-2-oxo-1-(2-oxo-2H-1,4-benzoxazin-3-yl)ethyl]-2-hydroxy-1,4-dioxo-3a,4-dihydro-1Hpyrrolo[2,1-c][1,4]benzoxazine-3-carboxylates 3a and 3b (Scheme 1). Compound 3a was isolated for the first time as the major product in the reaction of 1a with thioacetamide. The molecular and crystal structures of 3a were determined by X-ray analysis (Fig. 1). The described reaction is the first example of the isolation of the primary addition product of heterocyclic enamine to hetareno[e]pyrrole-2,3-diones, which
Scheme 1. EtO H O
R
O COOEt
N O 1a, 1b
O + R
N H
O
O
R
O
O 2a, 2b
OH 3a, 3b
1–3, R = H (a), Cl (b).
1321
N
O O COOEt
N
COOEt
O
O R
1322
KOBELEV et al. C9
C10
O2
C8
C4
C7 C11 O
3
C3
C1
C7 O4
C17
N1
C6
O1 N2
C2 C15
C12
O8
O6
C25
C22
C26 C
C19
O7
C16
C24
C23
21
O10
O5 C20 O9
C13 C18
C14
Fig. 1. Structure of the molecule of ethyl 3a-[2-ethoxy-2oxo-1-(2-oxo-2H-1,4-benzoxazin-3-yl)ethyl]-2-hydroxy-1,4dioxo-3a,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-3carboxylate (3a) according to the X-ray diffraction data.
confirms the scheme proposed b
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