Analysis of nmr spectra of benzaldehyde hepta-O-acetyl lactosyl - Nguyen Đinh Thanh

68 ANALYSIS OF NMR SPECTRA OF BENZALDEHYDE HEPTA-O-ACETYL-- LACTOSYL Đến tòa soạn 25 - 4 - 2013 Nguyen Đinh Thanh Faculty of Chemistry, College of Science, Hanoi National University Hoang Thị Kim Van Trường Đại học Công nghiệp Việt Trì (Phú Thọ) TÓM TẮT PHÂN TÍCH PHỔ NMR CỦA CÁC BENZALDEHYD HEPTA -O-ACETYL-- LACTOSYL THIOSEMICARBAZON Phổ 1H và 13C NMR của các benzaldehyd (peracetyl--lactosyl)thiosemicarbazone đã được thảo luận. Các tín hiệu cộng hưởng từ trong phổ NMR của chúng chỉ ra mối quan hệ giữa cấu trúc và vị trí của nhóm thế theo tương quan Hammett. Cấu hình  của các thiosemicarbazone này được xác nhận dựa vào hằng số ghép cặp J = 9.0–8.5 Hz giữa proton NH-4 của liên kết thiosemicarbazon và proton H-1’ trong hợp phần lactosyl. INTRODUCTION The synthetic method of hepta-O-acetyl- -lactosyl-thiosemicarbazones has been reported previously using microwave- assisted method [1]. In previous articles we announced the synthesis and properties of another aldehyde/ketone glycosyl per-O-acetylated thiosemicarbazones [2]. There are several discussions herein about the influence of structural factors to the positions of resonance signals in their 1 H and 13 C NMR spectra of hepta-O-acetyl-- lactosyl)-thiosemicarbazones of benzaldehydes and acetophenones. EXPERIMENTAL PART Substituted acetophenone hepta-O- acetyl--lactosyl thiosemicarbazones 1 (Scheme 1) were synthesized in bellow procedure [1]. Their 1 H and 13 C NMR spectra was recorded on FT-NMR Avance AV500 Spectrometer (Bruker, Germany) at 500.13 MHz and 125.76 MHz, respectively, using DMSO-d6 as solvent and TMS as an internal standard. Spectral data of 1 H and 13 C NMR were summarized in Tables 1 and 2. Tạp chí phân tích Hóa, Lý và Sinh học – Tập 19, Số 2/2014 69 General procedure for substituted benzaldehyde (hepta-O-acetyl-- lactosyl)-thiosemicarbazones (3LB a-v). A mixture of hepta-O-acetyl--maltosyl thiosemicarbazide 1L (1 mmol), benzaldehyde 2a-v (1 mmol), glacial acetic acid (0.5 ml) in absolute ethanol (in the presence of glacial acetic acid as catalyst) or glacial acetic acid (20 ml) was heated at reflux using domestic microwave oven TIFANY 750W in 5-7 min. The solvent was evaporated to one half the original volumes. The resulting colorless crystals were filtered by suction. The crude product when recrystallized from 96% ethanol to afford the title compounds 3 LB a-v. RESULTS AND DISCUSSION The selected 1 H and 13 C NMR spectral data of benzaldehyde hepta-O-acetyl-- lactosyl thiosemicarbazones 3LB a-v were listed in Table 1 and 2. From Tables 1 and 2 it’s shown that protons and carbon-13 atoms in these molecules have proper resonance signals in coresponding spectral regions which are characteristic for each atom type. Protons in NH-2 and NH-4 groups have signal at =12.18–11.67 ppm (singlet) and =8.88–8.06 ppm (doublet, J=9.5– 9.0 Hz), respectively. Proton of azomethin group (CH=N) shows chemical shift at =8.53–8.00 ppm (singlet). Aromatic protons have resonance signals in region at =8.33– 6.27 ppm, and the multicity of these signals depend on substituted patterns in benzene rings. Protons in CH3 group in acetate functions have signals in region at =2.06–1.92 ppm. Protons of disaccharide component have signals including in range from 5.90 ppm to 3.93 ppm. Protons on C-1” and C-2” carbon in pyranose ring A magnetically interact each to other with coupling constant, in this case, 3 J = 8.0–7.0 Hz that indicated that these both protons on C-1” and C-2” positions have trans-type interaction. This one comfirm that linkage between two pyranose rings, glucopyranose and galactopyranose, in this disaccharide is -(1→4)-glycoside bond that completely agree with the structure of -lactose. The distinct stucture pattern of galactopyranose ring, compared with the one of glucopyranose ring, is confirmed by coupling constant between H-4” and H-3” protons with 3J=3.75–2.5 Hz in galactopyranose ring, compared with the coupling constant 3 J=9.75–9.25 Hz in glucopyranose ring. Protons on C-1’ and C-2’ carbon atoms in ring B have similar interaction with coupling constant 3 J=9.0–8.5 Hz, in relation to H–H interaction of trans type, therefore, thiosemicarbazide linkage group is equatorial direction, i.e. all benzaldehyde hepta-O-acetyl--lactosyl thiosemicarbazones 3LB a-v have - anomeric configuration [4]. Other subrituents (hydroxy, methyl or methoxy) 70 also have specificsignals. The 13 C-NMR spectra of compound 3LB a-v showed the regions at  179.1–177.3 ppm (C=S), 170.2–169.0 ppm (C=O ester), 144.1– 138.9 ppm (azomethine CH=N), 146.4– 122.9 ppm (aromatic carbon atoms), 100.1–60.9 ppm (carbon atoms in lactose component), and 21.2–20.1 ppm (methyl carbon atoms in acetate groups). (Table 3). O O AcO AcO AcO OAc O NH 4 OAc AcO OAc C 3 NH 2 NH2 1 S + O HR 1L 2B a-v 3LB a-v EtOH solv., aceitc acid cat., MW oven 4" 5" O 1" 2" 3" OAc AcO OAc 6" OAc 4' 5' O 1' 2' 3' OAc AcO O 6' OAc NH 4 C 3 NH 2 N 1 S C 2'" 3'" 4'" 6'" 5'" R 1 R 2 ring Aring B 1'" where, R = 4-NO 2 (3B-a), 3-NO 2 (3B-b), 2-NO 2 (3B-c), 4-F (3B-d), 2,4-diCl (3B-e), 4-Cl (3B-f), 3-Cl (3B-g), 2-Cl (3B-h), 4-Br (3B-i), 2-OH-5-Br (3B-j), H (3B-k), 4-Me (3B-l), 4-iPr (3B-m), 4-OMe (3B-n), 3-OMe (3B-o), 2-OMe (3B-p), 4-OH (3B-q), 3-OH (3B-r), 2-OH (3B-s), 3-OMe-4-OH (3B-t), 3-OEt-4-OH (3B-u), 4-NMe 2 (3B-v). Scheme 1. Synthesis of benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones. The 1 H13C long-ranged interaction in HMBC spectrum of thiosemicarbazone molecule 3LB-r is shown in scheme bellow: 4" 5" O 1"2" 3" OAc AcO AcO 6" OAc 4' 5' O 1' 2' 3' OAc AcO O 6' OAc NH 4 C 3 NH 2 N 1 S C 2'" 3'" 4'" 6'" 5'" H H H H H H H H H H H H O H HH CH3 3LB-r (R=3-OMe): Homonuclear 1 H–1H interactions in COSY spectrum in compound 3LB-r are as follows:NH-2(11.95)H- 1’(5.79)H-2’(5.19)H-3’(5.31)H- 4’(3.81)H-5’(3.88)H-6’b(4.07)H- 6’a(4.30); H-1”(4.79)H-2”(4.88)H- 3”(5.15)H-4”(5.24); H-5”(4.24)H- 6”a(4.03) và H-6”b(4.03); H- 2’”(7.44)H-5’”(7.34) và H-6’”(7.31); H-4’”(7.00)H-5’”(7.34). The positions of resonance signals of protons NH-2, NH-4 and CH=N in compounds 3LB a-v (Fig. 2 A, B and C) had linear regression expressions as follows, respectively: NH-2 = 0.298 + 11.903 (R 2 = 0.96) NH-4 = 0.308 + 8.621 (R 2 = 0.93) CH=N = 0.145 + 8.065 (R 2 = 0.77) 71 Table 1. Selected 1 H NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones [ (ppm), multicity, J (Hz)] R 4-NO2 3-NO2 4-F 4-Cl 3-Cl 4-Br H Proton 3LB-a 3LB-b 3LB-d 3LB-f 3LB-g 3LB-i 3LB-k NH-2 12.16,s 12.10,s 11.90,s 11.95,s 11.99,s 12.00,s 11.95,s NH-4 8.88,d,9.0 8.83,d,9.0 8.66,d,9.0 8.70,d,9.0 8.75,d,9.0 8.70,d,9.0 8.67,d,9.5 CH=N 8.18,s 8.21,s 8.09,s 8.08,s 8.08,s 8.08,s 8.10,s H-2’” 8.10,d,9.0 8.58,s 7.88,d,5.5,8.5 7.85,d,8.5 7.98,s 7.82,d,8.5 7.82–7.80,m H-3’” 8.25,d,9.0 - 8.10,d,8.5 7.49,d,8.5 – 7.66,d,8.5 7.45–7.43,m H-4’” – 8.30,d,7.5 – – 7.48–7.44,m – 7.45–7.43,m H-5’” 8.25,d,9.0 7.72,t,8.0 8.10,d,8.5 7.49,d,8.5 7.48–7.44,m 7.66,d,8.5 7.45–7.43,m H-6’” 8.10,d,9.0 8.24,dd,1.5,8.0 7.88,d,5.5,8.5 7.85,d,8.5 7.70,dd,7.0,1.5 7.82,d,8.5 7.82–7.80,m H-1’ 5.88,t,9.0 5.86,t,9.0 5.85,t,9.25 5.85,t,9.0 5.85,t,9.0 5.90,t,9.0 5.86,t,9.25 H-2’ 5.24–5.21,m 5.20,t,9.5 5.19,1H,9.25 5.20,t,9.25 5.21,t,9.25 5.24,t,9.25 5.19,t,9.5 H-3’ 5.31,t,9.25 5.31,t,9.0 5.30,d,9.25 5.30,t,9.25 5.30,t,9.0 5.33,t,9.25 5.31,t,9.25 H-4’ 3.81,t,9.25 3.82,t,9.25 3.81,t,9.5 3.80,t,9.5 3.81,t,9.5 3.84,t,9.75 3.80,t,9.5 H-5’ 3.90–3.87,m 3.91–3.84,m 3.90–3.87,m 3.90–3.88,m 3.89,ddd, 1.5,5.5,10.0 3.84,t,9.75 3.89,ddd, 1.75,5.75,9.75 H-6’a 4.31,d,11.5 4.31,d,11.0 4.31,d,11.5 4.30,d,11.5 4.31,d,11.0 4.33,d,11.0 4.30,d,11.0 H-6’b 4.07,dd,5.5,12.5 4.08,dd,5.5,12.0 4.07,dd,5.5,11.0 4.08–4.05,m 4.07,5.75,12.25 4.09,dd,5.5,12.0 4.07,dd,5.5,12.0 H-1” 4.80,d,8.0 4.80,d,8.0 4.80,d,8.0 4.80,d,7.5 4.80,d,8.0 4.83,d,8.0 4.80,d,8.0 H-2” 4.88,t,8.75 4.88,dd,8.25,10.25 4.88,dd,3.25,10.5 4.88,t,9.0 4.88,dd,2.0,8.0 4.91,dd,3.0,11.5 4.87,dd,3.0,10.0 H-3” 5.15,dd,3.5,10.0 5.15,dd,3.5,10.0 5.17,dd,3.75,9.75 5.16,dd,3.5,10.0 5.16,dd,3.5,10.0 5.16,dd,3.75,10.25 5.15,dd,3.5,10.5 H-4” 5.24–5.21,m 5.24,d,3.5 5.24,d,3.5 5.24,d,3.5 5.24,d,3.5 5.28,d,3.5 5.24,d,3.5 H-5” 4.25,t,6.5 4.25,t,6.75 4.25,t,6.5 4.25,t,6.0 4.25,t,6.75 4.29,t,6.5 4.26,t,6.75 H-6”a 4.03,d,6.0 4.03,dd,2.25,6.75 4.04–4.02,m 4.04–4.03,m 4.04–4.00,m 4.07–4.05,m 4.04,dd,2.25,6.25 H-6”b 4.03,d,6.0 4.03,dd,2.25,6.75 4.04–4.02,m 4.04–4.03,m 4.04–4.00,m 3.94–3.91,m 4.04,dd,2.25,6.25 COCH3 2.11–2.01 2.11–1.91 2.11–2.01 2.11–1.91 2.11–1.90 2.15–1.94 2.11–1.90 72 Table 1(continuing). Selected 1 H NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones [ (ppm), multicity, J (Hz)] R 4-Me 4-iPr 4-OMe 3-OMe 4-OH 4-NMe2 Proton 3LB-l 3LB-m 3LB-n 3LB-o 3LB-q 3LB-v NH-2 11.86,s 11.87,s 11.81,s 11.95,s 11.76,s 11.67,s NH-4 8.59,d,9.5 8.57,d,9.0 8.55,d,9.0 8.62,d,9.0 8.51,d,9.5 8.41,d,9.5 CH=N 8.06,s 8.09,s 8.05,s 8.07,s 8.00,s 7.97,s H-2’” 7.69,d,8.5 7.72,d,8.0 7.75,d,8.5 7.44,s 6.81,d,8.5 7.59,d,8.5 H-3’” 7.25,d,8.5 7.30,d,8.0 6.99,d,8.5 – 7.64,d,8.5 6.72,d,8.5 H-4’” – – – 7.00,dd,1.5,8.0 – – H-5’” 7.25,d,8.5 7.30,d,8.5 6.99,d,8.5 7.34,t,8.0 7.64,d,8.5 6.72,d,8.5 H-6’” 7.69,d,8.5 7.72,d,8.0 7.75,d,8.5 7.31,t,8.0 6.81,d,8.5 7.59,d,8.5 H-1’ 5.84,t,9.0 5.83,t,9.25 5.83,t,9.25 5.79,t,9.0 5.83,t,9.25 5.82,t,9.0 H-2’ 5.21,t,9.25 5.18,t,9.5 5.18,t,9.25 5.18,t,9.25 5.18,t,9.25 5.17–5.14,m H-3’ 5.30,t,9.25 5.30,t,9.25 5.30,t,9.0 5.31,t,9.25 5.30,t,9.25 5.30,t,9.0 H-4’ 3.81,t,9.5 3.81,t,9.25 3.82–3.79,m 3.81,t,9.0 3.89–3.86,m 3.81,t,9.25 H-5’ 3.90–3.87,m 3.88–3.87,m 3.89–3.87,m 3.88,ddd,3.5,5.5, 10.0 3.80,t,9.75 3.88–3.85,m H-6’a 4.30,d,11.0 4.30,d,11.5 4.30,d,11.5 4.30,d,11.0 4.30,d,11.0 4.30,d,11.0 H-6’b 4.07,dd,5.75,12.25 4.09–4.03,m 4.09–4.05,m 4.07,dd,12.5,6.75 4.06,dd,5.5,9.5 4.09–4.05,m H-1” 4.80,d,8.0 4.80,d,8.0 4.80,d,7.5 4.79,d,7.5 4.80,d,8.0 4.79,d,7.5 H-2” 4.88,t,9.0 4.88,t,9.75 4.88,t,9.25 4.88,dd,10.0,3.0 4.87,dd,10.0,3.0 4.88,t,9.0 H-3” 5.15,dd,3.75,10.25 5.15,dd,10.5,3.75 5.15,dd,10.0,3.0 5.15,dd,10.5,3.5 5.16,dd,10.0,4.0 5.17–5.14,m, H-4” 5.24,d,3.5 5.24,d,3.5 5.24,d,3.0 5.24,d,3.5 5.24,d,3.5 5.25,d,2.5 H-5” 4.25,t,6.5 4.25,t,5.75 4.24,t,6.75 4.24,t,6.75 4.25,t,6.75 4.25,t,6.0 H-6”a 4.04–4.03,m 4.09–4.03,m 4.04–4.03,m 4.03,d,6.5 4.03–4.02,m 4.04–4.03,m H-6”b 4.04–4.03,m 4.09–4.03,m 4.04–4.03,m 4.03,d,6.5 4.03–4.02,m 4.04–4.03,m COCH3 2.11–1.90 2.11–1.90 2.11–1.91 2.11–2.01 2.11–1.90 2.11–1.91 Other protons 2.34,s,4’”-Me 2.92,q,7.0,4’”-CH(CH3)2; 1.21,d,7.0,4’”-CH(CH3)2 3.81,s,4’”-OMe 3.83,s,3’”-OMe 9.97,s,4’”-OH 2.97,s,6H,4’”-N(Me)2 73 Table 2. Selected 13 C NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones,  (ppm) R 4-NO2 3-NO2 4-F 4-Cl 3-Cl 4-Br H 4-Me 4-iPr 4-OMe 3-OMe 4-OH 4-NMe2 Cacbon 3LB-a 3LB-b 3LB-d 3LB-f 3LB-g 3LB-i 3LB-k 3LB-l 3LB-m 3LB-n 3LB-o 3LB-q 3LB-v C=S 178.8 178.7 178.4 178.3 178.6 178.4 178.3 178.2 178.2 177.8 178.4 177.7 177.3 COCH3 170.2– 169.0 170.2– 69.1 170.2– 169.1 170.5– 169.4 170.1– 169.0 170.2– 169.0 170.3– 169.1 170.2– 169.0 170.2– 169.0 170.5– 169.4 170.2– 169.0 170.2– 169.0 170.2– 169.0 CH=N 141.1 141.6 142.6 142.7 142.2 142.5 143.7 143.9 143.8 144.1 143.5 144.1 144.8 C-1’” 140.2 135.7 130.4 132.5 135.9 133.0 133.7 131.0 131.4 126.0 135.1 124.6 120.8 C-2’” 128.4 121.9 129.7 129.8 126.3 129.4 128.7 127.5 127.6 129.2 111.4 129.4 128.9 C-3’” 123.8 148.4 115.7 128.8 133.7 131.7 127.6 129.3 126.6 114.2 159.6 115.6 111.6 C-4’” 147.8 124.4 163.3 134.9 130.5 123.5 130.3 140.2 150.9 161.1 116.5 159.6 151.7 C-5’” 123.8 130.2 115.7 128.8 129.8 131.7 127.6 129.3 126.6 114.2 129.6 115.6 111.6 C-6’” 128.4 133.4 129.7 129.8 126.7 129.4 128.7 127.5 127.6 129.2 120.7 129.4 128.9 C-1’ 81.3 81.3 81.3 81.2 81.3 81.2 81.2 81.2 81.1 81.1 81.2 81.1 81.1 C-2’ 71.2 71.1 71.1 70.9 71.1 71.1 71.1 71.1 71.0 70.9 70.9 71.1 71.0 C-3’ 72.8 72.7 72.7 72.6 72.7 72.7 72.7 72.7 72.7 72.6 72.5 72.7 72.7 C-4’ 76.0 76.0 76.0 75.9 76.0 76.0 76.1 76.0 76.0 75.9 76.1 76.1 76.1 C-5’ 73.4 73.5 73.4 73.5 73.4 73.4 73.3 73.4 73.4 73.5 73.4 73.3 73.4 C-6’ 62.4 62.4 62.4 62.2 62.3 62.4 62.4 62.3 62.3 62.2 62.3 62.3 62.3 C-1” 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 C-2” 68.9 68.9 68.9 68.8 68.9 68.8 68.8 68.9 68.8 68.8 68.8 68.8 68.9 C-3” 70.4 70.4 70.4 70.3 70.4 70.4 70.4 70.4 70.3 70.3 70.4 70.3 70.4 C-4” 67.1 67.1 67.1 67.0 67.1 67.1 67.1 67.1 67.1 67.1 67.1 67.1 67.1 C-5” 69.7 69.8 69.8 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7 C-6” 61.0 61.0 61.0 60.9 61.0 60.9 61.0 60.9 60.9 60.9 60.9 60.9 60.9 COCH3 20.7– 20.3 20.7– 20.3 20.7– 20.2 20.5– 20.1 20.8– 20.2 20.7– 20.4 20.7– 20.3 20.6– 20.2 20.6– 20.2 20.5– 20.1 20.6– 20.2 20.7– 20.3 20.6– 20.2 Note: Other (13C): 21.0,4’”-Me (3LB-l); 33.4.5,4’”-CH(Me)2; 23.5,4’”-CH(Me)2 (3LB-m); 55.2,4’”-OCH3 (3LB-n); 55.2,3’”-OCH3 (3LB-o); 40.0,4’”-N(Me)2 (3LB-v). 74 Conversely, carbon atom in imine group were affected clearly by these substituents with opposite trend: the donating ones (with  < 0, such as 4-OH, 4-OMe, 4-Me on benzene ring of benzadehyde) caused signal to be shifted to upfield region, and the withdrawing ones (with  < 0, such as 3-NO2-4-Cl, 4- NO2, 3-NO2-4-Me, 3-NO2-4-OMe, 4-Cl, 4-Br in benzadehyde series) caused the resonance of this carbon atom to be in downfield region (Table 3). These tendencies could be shown in equations as follows (Fig. 2D). CH=N = 2.458σ + 143.31 (R 2 = 0.91) Figure 2. Linear relationships between NH-2 (A), NH-4 (B), CH=N (C) và C=N (D) and Hammett’s  in compouds 3LBa-v CONCLUSIONS The 1 H and 13 C NMR spectra of substituted benzaldehyde peracetyled - lactosyl)thiosemicarbazones have been studied and discussed. The magnetic signals in their NMR spectra show the relationships between the structural features and positions of the substituted groups in benzene ring. 75 Acknowledgments. Financial support for this work was provided by Vietnam's National Foundation for Science and Technology Development (NAFOSTED). REFERENCES 1. (a) Nguyen Dinh Thanh, Hoang Thi Kim Van, Nguyen Thuy Linh, Do Thi Thuy Giang, Tạp chí Khoa học và Công nghệ, T. 48, No. 2A, (2010); (b) Nguyen Dinh Thanh, Hoang Thi Kim Van, Nguyen Hai Ha, Do Thi Thuy Giang, Journal of Chemistry (VAST) (accepted). 2. 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