New pathway to the synthesis of substituted 4H-3,1-benzoxazines

Article abstract of DOI:10.1023/A:1025611632368

The intramolecular rearrangement of N-acyl-2-cyclopropylanilines by the action of protic acids gives substituted 4H-3,1-benzoxazines. The reaction proceeds in high yield through the formation of benzoxazine precursors, namely, the corresponding 3,1-benzoxazinium ions, which are stable in acid solution. N-Acylamino-2-alkenylbenzenes, in which the double bond of the alkyl chain is conjugated with the benzene ring, are capable of undergoing a similar rearrangement.

Full text of DOI:10.1023/A:1025611632368

Chemistry of Heterocyclic Compounds, Vol. 39, No. 6, 2003
NEW PATHWAY TO THE SYNTHESIS OF
SUBSTITUTED 4H-3,1-BENZOXAZINES
S. S. Mochalov, R. A. Gazzaeva, A. N. Fedotov, Yu. S. Shabarov, and N. S. Zefirov
The intramolecular rearrangement of N-acyl-2-cyclopropylanilines by the action of protic acids gives
substituted 4H-3,1-benzoxazines. The reaction proceeds in high yield through the formation of
benzoxazine precursors, namely, the corresponding 3,1-benzoxazinium ions, which are stable in acid
solution. N-Acylamino-2-alkenylbenzenes, in which the double bond of the alkyl chain is conjugated
with the benzene ring, are capable of undergoing a similar rearrangement.
Keywords: N-acylamino-2-alkenylbenzenes, N-acyl-2-cyclopropylanilines, 4H-3,1-benzoxazines,
4H-3,1-benzoxazinium ions, rearrangement.
The chemical and biological properties of 4H-3,1-benzoxazines have hardly been studied, largely due to
the lack of general and efficient methods for their synthesis. Individual 4H-3,1-benzoxazines have been
synthesized by intramolecular cyclization of the corresponding o-acylaminobenzyl alcohols or o-aminobenzyl
chlorides [1]. However, limitations related to difficulty in obtaining these chlorides have prevented the use of
these reactions for the synthesis of 4H-3,1-benzoxazines. Examination of the possible schemes for these
chlorides from o-acylaminobenzyl alcohols would lead us to expect formation of the desired heterocyclic
products if the starting aromatic substrate has a fragment, in which a benzylic carbenium site can be generated,
while an NH–C(R)=O group exists adjacent to this fragment, in which the oxygen atom is capable of
manifesting nucleophilic properties.
We have found that N-acyl-2-cyclopropylanilines 3-17 (Table 1) indeed are capable of converting to the
corresponding 4H-3,1-benzoxazines 18-32 in high yield under the conditions of the acid-catalyzed reactions of
phenylcyclopropanes [2-4] (Table 2). This reaction is initiated by the proton-catalyzed opening of the
cyclopropane ring and generation of benzylic carbenium ion A. Subsequent intramolecular stabilization of ions
A by the nucleophilic oxygen atom of the amide fragment leads to heterocyclic ions B, which are precursors of
neutral rearrangement products 18-32.
Special experiments showed that benzoxazinium ions B formed immediately upon mixing the
rearrangements are so stable in concentrated sulfuric acid at 20°C that they do not undergo isomerization for at
least 3-4 months. This stability of heterocyclic ions B permits us to carry out the reaction at 20°C. The yields of
4H-3,1-benzoxazines in this case are almost as high but the reaction is completed in much less time (Table 3).
In test variants of this rearrangement under milder conditions, we attempted to use trifluoroacetic acid
as the initiator for opening the cyclopropane ring since the small ring in phenylcyclopropane is opened by the
action of this acid [5].
__________________________________________________________________________________________
M. V. Lomonosov Moscow State University, Moscow 119899, Russia; e-mail: fed@org.chem.msu.ru.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 922-929, June, 2003. Original article
submitted November 17, 2000.
794
0009-3122/03/3906-0794$25.00©2003 Plenum Publishing Corporation

R1
R1
R2COCl, 3N NaOH
20 oC
H2SO4
–20 oC
NHCOR2
NH2
R1
3–17
1, 2
R1
R1
1. H2O, 0 oC
2. Na2CO3
O
O
+
+
NHCOR2
N
R
N
R2
H
B
A
18–32
1, 3-11, 18-26 R1 = H; 2, 12-17, 27-32, R1 = Me; 3, 13, 18, 28 R2 = Ph; 4, 10, 19, 25
R2 = p-MeC6H4; 5, 14, 20, 29 R2 = o-ClC6H4; 6, 15, 21, 30 R2 = p-ClC6H4; 7, 16, 22, 31
R2 = o-BrC6H4; 8, 17, 23, 32 R2 = p-BrC6H4; 9, 24 R2 = m-MeOC6H4;
11, 26 R2 = p- O2NC6H4; 12, 27, R2 = Me
In the case of anilide 4, we found that trifluoroacetic acid cannot initiate the rearrangement at 20°C.
However, anilide 4 is converted quantitatively to 4-ethyl-2-(p-tolyl)-4H-3,1-benzoxazinium ion (19a) upon
warming the solution of this amide in trifluoroacetic acid.
We should note that the use of trifluoroacetic acid as the initiator for the rearrangement and the solvent
yielded further evidence for the formation of the corresponding ionic precursors of 3,1-benzoxazines 18-32
directly in solutions of this acid.
H
H2O, 0 oC,
TFA
O
Na2CO3
19
+
70 oC
TFA, 20 oC
Me
NHCO
N
H
4
Me
19a
This evidence is found in the 1H NMR spectra of the reaction mixture obtained upon treating acylaniline
4 upon warming and recooling to room temperature, and of authentic 4-ethyl-2-(p-tolyl)-4H-3,1-benzoxazine
(19) in the same acid (the high viscosity of the solutions of 4 and 19 in concentrated sulfuric acid prevented
1
high-quality H NMR spectra). The two spectra proved identical and the multiplicity of the proton signals as
well as the integral intensities and chemical shifts correspond to ion 19a (Table 2).
Thus, trifluoroacetic acid may be used in the synthesis of 4H-3,1-benzoxazines from the corresponding
N-acyl-2-cyclopropylanilines. In general, this procedure is preferable to using concentrated sulfuric acid since
trifluoroacetic acid has virtually no oxidizing properties.
Then, in order to demonstrate the general nature of the synthesis of substituted 4H-3,1-benzoxazines
from anilides containing a substituent in the ortho position to the amide fragment, from which a benzylic
carbenium site can be generated by the action of acid, we synthesized an anilide with a propenyl group in the
ortho position (34) and studied its conversion upon the action of trifluoroacetic acid. Thus, N-acyl-2-
alkenylanilines 34 upon the action of trifluoroacetic acid, similar to the corresponding cyclopropane derivatives,
are capable of rearrangement to give 4H-3,1-benzoxazines. This reaction is accomplished under milder
conditions than for the rearrangement of the cyclopropylanilides.
795

TABLE 1. Characteristics of N-Acyl-o-cyclopropylanilides 3-17 and o-Propenylanilide 34
Found, %
1Н NMR spectrum, δ, ppm. (J, Hz)*
——————
Com-
Empirical
formula
Yield,
%
Calculated, %
mp, °С
pound
С
3
Н
4
N
5
Aliphatic protons
7
Aromatic protons
8
NH*
9
1
3
2
6
10
78
79
С16Н15NO
C17H17NO
81.38
80.98
6.61
6.37
5.86
5.90
145-146
123-124
0.71 (2Н, m); 0.92 (2Н, m);
2.08 (1Н, m)
7.04 (1Н, m); 7.21 (2Н, m); 7.46 (1H, m); 9.83 (1H, br. s)
7.55 (3Н, m); 8.01 (2Н, m)
81.09
6.81
5.46
0.52 (2Н, m); 0.93 (2Н, m);
7.16 (1Н, m); 7.29 (1Н, m);
8.01 (1H, br. s)
4
81.24
6.82
5.57
1.84 (1Н, m); 2.41 (3H, s)
7.33 (2Н, d, J = 8.2); 7.39 (1Н, m);
7.78 (2Н, d, J = 8.2); 7.88 (1Н, s)
C16H14ClNO
70.21
70.72
5.01
5.19
4.95
5.15
114-115
0.72 (2Н, m); 0.97 (2Н, m);
1.81 (1Н, m)
7.09 (1Н, m); 7.21 (1Н, m); 7.29 (1Н, m); 8.51 (1Н, br. s)
7.41 (3Н, m); 7.82 (1Н, m);
72
5
8.33 (1Н, d, J = 8.0)
C16H14ClNO
C16H14BrNO
C16H14BrNO
70.41
70.72
5.16
5.19
5.01
5.15
122-123
146-147
147-148
0.63 (2Н, m); 0.93 (2Н, m);
2.07 (1Н, m)
7.01 (1Н, m); 7.19 (2Н, m); 7.43 (1Н, m);
9.81 (1Н, s)
9.79 (1Н, s)
8.55 (1Н, s)
81
74
78
6
7
8
7.49 (2Н, d, J = 8.8); 8.02 (2Н, d, J = 8.8)
60.69
4.38
4.29
0.66 (2Н, m); 0.96 (2Н, m);
6.99 (1Н, m); 7.18 (2Н, m); 7.39 (1Н, m);
7.48 (1Н, m); 7.56 (2Н, m); 7.69 (1Н, m)
60.77
4.46
4.42
2.12 (1Н, m)
60.61
60.77
4.52
4.46
4.31
4.42
0.72 (2Н, m); 1.02 (2Н, m);
1.87 (1Н, m)
7.09 (1Н, m); 7.25 (2Н, m);
7.68 (2Н, d, J = 8.6);
7.79 (2Н, d, J = 8.6); 8.41 (1Н, d, J = 8.8)
C17H17NO2
C17H17NO2
76.62
76.38
6.39
6.41
5.09
5.24
77-78
0.63 (2Н, m); 0.96 (2Н, m);
2.09 (1Н, m); 3.88 (3Н, s)
6.99-7.22 (4Н, m); 7.39 (1Н, t);
9.71 (1Н, s)
9.51 (1Н, s)
82
84
9
7.49 (1Н, m); 7.57 (2Н, m)
76.46
6.27
5.17
106-107
0.64 (2Н, m); 0.93 (2Н, m);
7.01 (3Н, 2d); 7.15 (2Н, m);
10
76.38
6.41
5.24
2.08 (1Н, m); 3.87 (3Н, s)
7.51 (1Н, d, J = 8.4); 7.98 (2Н, d, J = 8.2)

TABLE 1 (continued)
1
2
3
4
5
6
7
8
9
10
64
73
76
81
C16H14N2O3
C12H15NO
C17H17NO
C17H16ClNO
68.22
68.07
4.77
4.99
9.21
9.92
153-154
112-113
108-110
38-40
0.68 (2Н, m); 0.95 (2Н, m);
2.09 (1Н, m)
0.81 (4Н, s); 1.27 (3Н, s);
7.01 (1Н, m); 7.19 (2Н, m); 7.41 (1Н, m);
8.25 (2Н, d, J = 9.0); 8.37 (2Н, d, J = 9.0)
10.11 (1Н, s)
8.57 (1Н, s)
9.45 (1Н, s)
9.27 (1Н, s)
11
75.92
7.77
7.23
7.05 (1Н, t); 7.16 (1Н, t);
12
13
14
76.16
7.99
7.40
2.19 (3Н, s)
7.27 (1Н, d, J = 8.0); 7.57 (1Н, d, J = 8.0)
81.01
81.24
6.69
6.82
5.41
5.57
—
0.72 (2Н, s); 0.88 (2Н, s);
1.35 (3Н, s)
0.72 (2Н, s); 0.85 (2Н, s);
7.12-7.77 (9Н, m)
71.54
5.83
7.16 (1Н, t); 7.25 (1Н, t);
7.37 (1Н, d, J = 7.8); 7.51 (3Н, m);
7.70 (2Н, m)
71.45
5.64
1.32 (3Н, s)
C17H16ClNO
71.12
71.45
5.74
5.64
4.71
4.90
96-97
0.91 (4Н, m); 1.36 (3Н, s)
7.09 (1Н, m); 7.32 (2Н, m);
8.71 (1Н, s)
76
15
7.51 (2Н, d, J = 8.2);
7.87 (2Н, d, J = 8.2); 8.43 (1Н, d, J = 8.0)
C17H16BrNO
C17H16BrNO
C17H17NO
62.01
61.83
4.83
4.88
4.42
4.24
59-60
0.72 (2Н, m); 0.83 (2Н, m);
1.32 (3Н, s)
7.27 (2Н, m); 7.37-7.65 (5Н, m);
9.43 (1Н, br. s)
78
77
72
16
17
34
7.78 (1Н, d, J = 8.2)
62.25
4.82
4.47
104-106
137-138
0.71 (2Н, s); 0.86 (2Н, s);
7.23 (1Н, m); 7.39 (1Н, m); 7.57 (1Н, m); 9.45 (1Н, br. s)
7.77 (2Н, d, J = 9.0); 7.93 (2Н, d, J = 9.0)
61.83
4.88
4.24
1.29 (3Н, s)
81.03
81.24
6.68
6.82
5.31
5.57
1.29 (3Н, d, J = 6.4); 2.41 (3Н, s);
6.16 (1Н, m, =СН–СН3);
7.16 (1Н, m); 7.29 (1Н, m);
9.71 (1Н, s)
7.31 (2Н, d, J = 8.2); 7.36 (1Н, m);
6.51 (1Н, m, СН=СН–СН3)
7.57 (1Н, m); 7.93 (2Н, d, J = 8.2)
_______
* Spectra for compounds 3, 6, 7, 9-14, 16, 17, 34 taken in DMСO-d6, for compounds 4, 5, 8, 15 – in СDCl3.

TABLE 2. Characteristics of 2-R-4H-3,1-Benzoxazines 18-32*
Found, %
——————
Com-
Empirical
formula
Yield,
%
1Н NMR spectrum, ppm (J, Hz)*2
Calculated, %
pound
C
3
H
4
N
5
1
18
2
6
7
С16Н15NО
81.13
80.98
6.52
6.37
6.28
5.90
1.01 (3Н, t, СН3–СН2–); 1.93 (2Н, m, СН3–СН2–); 5.28 (1Н, t, Н-4 benzoxazine);
6.81-7.57 (7Н, m); 7.92-8.16 (2Н, m, ArH)
91
85
—
88
81
86
С17Н17NO
79.85
6.61
5.41
1.05 (3H, t, CH3–CH2–); 1.92 (2H, m, CH3–CH2–); 2.41 (3H, s, CH3–Ar); 5.45 (1H, t, H-4 benzoxazine);
19
81.24
6.82
5.57
7.17 (3H, m); 7.28 (3H, m); 7.94 (2H, d, J = 8.0, ArH)
С17Н17NO +H+
C16H14ClNO
C16H14ClNO
C16H14BrNO
—
—
—
1.25 (3Н, t, СН3–СН2–); 2.31 (2Н, m, СН3–СН2–); 2.56 (3Н, s, СН3); 6.12 (t, 4-Н benzoxazine);
19a
20
7.36 (1Н, m); 7.50 (1Н, m); 7.56 (4Н, m); 8.11 (2Н, d, Jo = 8.2, ArH)
70.41
70.72
5.10
5.19
4.90
5.15
1.08 (3Н, t, СН3–СН2–); 2.04 (2Н, m, СН3–СН2–); 5.46 (1Н, t, Н-4 benzoxazine); 7.04 (1Н, d, J = 8.0);
7.23 (1Н, m); 7.28-7.39 (4Н, m); 7.45 (1Н, dd, J = 8.0 and 1.6); 7.74 (1Н, dd, J = 8.0, J = 2.0, ArH)
70.58
4.91
5.01
1.07 (3Н, t, СН3–СН2–); 1.91 (2Н, m, СН3–СН2–); 5.34 (1Н, m, Н-4 benzoxazine); 6.99 (1Н, d, J = 8.0);
21
70.72
5.19
5.15
7.25 (3Н, m); 7.41 (2Н, d, J = 8.2); 8.11 (2Н, d, J = 8.2, ArH)
60.21
60.77
4.23
4.46
4.18
4.42
1.06 (3Н, t, СН3–СН2–); 2.06 (2Н, m, СН3–СН2–); 5.48 (1Н, t, Н-4 benzoxazine); 7.05 (1Н, d, J = 7.8);
7.24 (1Н, dt, Jо = 7.8, Jm = 2.2); 7.28-7.35 (3Н, m); 7.38 (1Н, dt, Jо = 7.8, Jm = 1.4);
7.69 (1Н, dd, Jo = 7.8, Jm = 1.4); 7.69 (1Н, dd, Jо = 7.8, Jm = 2.2, ArH)
22
C16H14BrNO
C17H17NO2
C17H17NO2
60.39
60.77
4.31
4.46
4.21
4.42
1.05 (3Н, t, СН3–СН2–); 1.91 (2Н, m, СН3–СН2–); 3.85 (3Н, s, ОСН3); 5.47 (1Н, t, Н-4 benzoxazine);
87
90
88
23
24
25
7.07-7.43 (6Н, m); 7.61 (1Н, s); 7.69 (1Н, d, J = 8.4, ArH)
76.01
6.11
4.99
1.05 (3Н, t, СН3–СН2–); 1.90 (2Н, m, СН3–СН2–); 3.87 (3Н, s, ОСН3); 5.44 (1Н, t, Н-4 benzoxazine);
7.01 (2Н, d, J = 8.8); 7.15 (3Н, m); 7.29 (1Н, t); 8.05 (2Н, d, J = 8.8, ArH)
76.38
6.41
5.24
76.12
76.38
6.09
6.41
5.01
5.24
1.05 (3Н, t, СН3–СН2–); 1.95 (2Н, m, СН3–СН2–); 5.58 (1Н, t, Н-4 benzoxazine);
7.15-7.38 (4Н, m); 8.38 (4Н, s, ArH)

TABLE 2 (continued)
1
2
3
4
5
6
7
C16H14N2O3
C12H15NO
67.74
68.07
4.77
4.99
9.61
9.92
1.05 (3Н, t, СН3–СН2–); 1.95 (2Н, m, СН3–СН2–); 5.58 (1Н, t, Н-4 benzoxazine);
7.15-7.38 (4Н, m); 8.38 (4Н, s, ArH)
71
74
97
84
84
92
89
26
75.88
7.76
7.14
0.84 (t, СН3–СН2–); 1.61 (3Н, s, СН3); 1.81-1.94 (2Н, m, СН3–СН2–); 2.11 (3Н, s, СН3);
27
76.16
7.99
7.40
6.98-7.26 (4Н, m, ArH)
C17H17NO
80.95
81.24
6.66
6.82
5.31
5.57
0.97 (t, СН3–СН2–); 1.74 (3Н, s, СН3); 2.07 (2Н, m, СН3–СН2–); 7.12 (1Н, m); 7.29 (2Н, m);
7.42 (3Н, m); 8.12 (2Н, m, ArH)
28
C17H16NOCl
C17H16NOCl
C17H16NOBr
C17H16NOBr
71.01
5.22
4.82
0.99 (t, СН3–СН2–); 1.75 (3Н, s, СН3); 2.14 (2Н, m, СН3–СН2–); 7.09 (1Н, d, J = 8.0);
29
71.45
5.64
4.90
7.21-7.48 (6Н, m); 7.84 (1Н, d, J = 8.0, ArH)
70.95
71.45
5.31
5.64
4.68
4.90
0.94 (t, СН3–СН2–); 1.71 (3Н, s, СН3); 2.01 (2Н, m, СН3–СН2–); 7.08 (1Н, d, J = 8.0); 7.19 (1Н, m);
7.24 (2Н, m); 7.41 (2Н, d, J = 8.2, ArH)
30
61.66
4.71
4.01
0.99 (t, СН3–СН2–); 1.76 (3Н, s, СН3); 2.08 (2Н, m, СН3–СН2–); 7.07 (1Н, m); 7.19-7.41 (5Н, m);
31
61.83
4.88
4.24
7.67 (2Н, m, ArH)
61.53
61.83
4.76
4.88
3.96
4.24
0.88 (t, СН3–СН2–); 1.67 (3Н, s, СН3); 1.98 (2Н, m, СН3–СН2–); 7.14-7.32 (4Н, m); 7.68 (2Н, d, J = 8.2);
8.01 (2Н, d, J = 8.2, ArH)
32
_______
* Mp, °C: 21 47-48; 23 44-45; 25 46-47; 26 77-78, other compounds are viscous oils.
*2 Spectra for compounds 18-20, 22-32 obtained in СDCl3, for compound 21 – in DMSO-d6, for compound 19а – in
CF3COOH, internal standard TMS.

TABLE 3. Effect of the Isomerization Temperature (IT) on the
Rearrangement of N-(4-Methylbenzoyl)-2-cyclopropylaniline 4 by the
Action of Concentrated Sulfuric Acid
IT, °С
Reaction time, h
Product yields, %
-35
-20
0
3.5
2.0
1.0
0.5
88
93
93
94
+20
Me
COCl
1. TFA, 20 oC
2. H2O, 0 oC
19
NH2
Me
NHCO
33
34
Since substituted alkenylanilines 33 are readily easily formed from the corresponding
cyclopropylanilines, 4H-3,1-benzoxazines, which cannot be synthesized from cyclopropylanilides by the action
of concentrated sulfuric acid, likely can be prepared through the scheme shown above.
EXPERIMENTAL
1
The H NMR spectra were taken on a Varian VXR-400 spectrometer at 400 MHz in CDCl3 with TMS
as the internal standard and a Bruker AM-300 spectrometer at 300 MHz in DMSO-d6. The purity of the products
was carried out by thin-layer chromatography on grade II alumina plates using 1:1:3 ether–chloroform–hexane
as the eluent. The indices of the products synthesized for the first time are given in Tables 1 and 2.
2-Cyclopropylanilines 1 and 2 were obtained by the reduction of the corresponding
2-nitrophenylcyclopropanes as described in our previous work [6, 7]. N-(4-Nitrobenzylidene)-2-
cyclopropylaniline was obtained by the condensation of 2-cyclopropylaniline 1 with p-nitrobenzaldehyde
according to our previous procedure.
2-Propenylaniline (33). A sample of N-(4-nitrobenzylidene)-2-cyclopropylaniline (2.66 g, 10 mmol)
was added in small portions to concentrated sulfuric acid (30 ml), maintaining the temperature at -20°C, and
stirred at this temperature for 1 h. The reaction mixture was poured onto ground ice (100 g) and extracted with
ether to remove p-nitrobenzaldehyde. The aqueous layer was made slightly basic by adding aqueous NaOH and
extracted with ether. The ethereal extract was dried over MgSO4. Evaporation of the solvent and distillation of
the residue in vacuum gave 0.85 g (64%) 33; bp 85-87°C (2 mm Hg) (bp 63-65°C (0.6 mm Hg) [8]).
N-Acyl-2-cyclopropylanilines (3-17) and N-(4-Methylbenzoyl)-2-propenylaniline (34) (General
Method). A sample of acid chloride derivative of the corresponding acid (1.5 mmol) in dioxane (3 ml) and 3 N
NaOH (5.6 g) was added with stirring at the same time gradually to a solution of 1 (or 2) or 33 (1.5 mmol) in
dioxane (40 ml). The reaction mixture was stirred for 1 h at 20°C and poured into water (150 ml). The
crystalline precipitate formed was filtered off, washed with water, and recrystallized from ethanol.
Isomerization of N-Acyl-2-cyclopropylanilines 3-17 by the Action of Concentrated Sulfuric Acid.
A sample of the corresponding N-acylaminophenylcyclopropane (1.5 mmol) was added in portions with stirring
to concentrated sulfuric acid (2.5 ml) cooled to -10°C. The temperature was brought to 20°C. The reaction
mixture was stirred for 30 min, poured into ice water (50 ml), and neutralized by adding Na2CO3. The organic
products were extracted using two 15-ml chloroform portions and the extract was dried over MgSO4. After
800

evaporation of the solvent, the residue was subjected to chromatography on grade-II alumina using 1:3 ether–
hexane as the eluent. The yields of 4H-3,1-benzoxazines 18-32 and their physicochemical indices are given in
Table 2.
Isomerization of N-(4-Methylbenzoyl)-2-propenylaniline (34) by the Action of Trifluoroacetic
Acid. A sample of 34 (0.38 g, 1.5 mmol) was added in portions to trifluoroacetic acid (3 ml). After 15 min, the
temperature of the reaction mixture had risen to 30°C. The mixture was cooled to 20°C and poured into ice
water (50 ml). Then, the mixture was treated and the desired product was isolated as described above. The yield
of 4-ethyl-2-(p-tolyl)-4H-3,1-benzoxazine (19) 0.33 g (88%).
Benzoxazines 21, 25, and 30 were obtained from 6, 10, and 15 in 85, 91, and 93% yield, respectively,
according to an analogous procedure.
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