Compound characterization data

Victoria O. Kis, A. Dina Dilinaer, Mana Dashti, Ezequiel Silva-Nigenda, Dominique Leckie, John J. Hayward, and John F. Trant. “Some thioester syntheses love DIC: A case study on functionalizing amino acids with O-protected mercaptoethanol.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15008056/v1

2-((tert-butyldimethylsilyl)oxy)ethane-1-thiol
Identifier	Compound 4
Density	0.887 g/mL
¹H NMR (301 MHz, CDCl₃), δ	3.72 (t, J = 6.4 Hz, 2H), 2.62 (dt, J = 8.3, 6.4 Hz, 2H), 1.52 (d, J = 8.3 Hz, 1H), 0.90 (d, J = 2.6 Hz, 9H), 0.08 (d, J = 6.2 Hz, 6H)
¹³C{¹H} NMR (76 MHz, CDCl₃), δ	65.20, 27.45, 26.03, 25.82, 18.46, −5.13

S-(2-((tert-butyldimethylsilyl)oxy)ethyl) (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-4-((tert-butoxycarbonyl)amino)butanethioate
Identifier	Compound 10
¹H NMR (300 MHz, CDCl₃), δ	7.76 (pseudo-dq, J = 7.7, 1.1 Hz, 2H, 2H), 7.67–7.49 (m, 2H), 7.40 (pseudo-dd, J = 7.5, 1.5 Hz, 2H), 7.32 (pseudo-tdd, J = 7.5, 2.5, 1.1 Hz, 2H), 5.85 (d, J = 9.0 Hz, 1H), 4.87 (s, 1H), 4.54 – 4.44 (m, 2H), 4.40 (dd, J = 10.7, 7.1 Hz, 1H), 4.25 (t, J = 7.1 Hz, 1H), 3.71 (t, J = 6.6 Hz, 2H), 3.12–2.92 (m, 3H), 2.05 (s, 1H), 1.95 – 1.83 (m, 1H), 1.46 (s, 9H), 0.88 (s, 9H), 0.05 (s, 6H)
¹³C{¹H} NMR (76 MHz, CDCl₃), δ	200.71, 171.27, 156.27, 143.95, 143.76, 141.44, 127.85, 127.21, 125.27, 120.10, 79.77, 67.31, 61.84, 60.51, 58.82, 47.33, 36.62, 33.23, 31.80, 28.54, 25.95, 25.79, 21.15, 18.37, 14.31, −5.19
HRMS (ESI), C₃₂H₄₆N₂O₆SSi, m/z	[M+H]⁺ theoretical 615.2919, observed 615.2899, mass accuracy 3.19 ppm; [M+Na]⁺ theoretical 637.2734, observed 637.2734, mass accuracy 0.64 ppm; [M+K]⁺ theoretical 653.2477, observed 653.2466, mass accuracy 1.75 ppm

S-(2-((tert-butyldimethylsilyl)oxy)ethyl) (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-((tert-butoxycarbonyl)amino)pentanethioate
Identifier	Compound 11
¹H NMR (301 MHz, CDCl₃), δ	7.77 (pseudo-dd, J = 7.5, 1.2 Hz, 2H), 7.63 (pseudo-t, J = 6.3 Hz, 2H), 7.44 – 7.36 (m, 2H), 7.31 (pseudo- td, J = 7.4, 1.2 Hz), 2H, 5.56 (bd, J = 8.6 Hz, 1H), 4.72–4.30 (m, 4H), 4.24 (t, J = 6.9 Hz, 1H), 3.70 (t, J = 6.5 Hz, 2H), 3.38–3.10 (m, 2H), 3.04 (dt, J = 13.0, 6.9 Hz, 2H), 2.00–1.87 (m, 1H), 1.71–1.60 (m, 1H), 1.59-1.40 (m, 2H), 1.45 (s, 9H), 0.88 (s, 9H), 0.05 (s, 6H)
¹³C{¹H} NMR (76 MHz, CDCl₃), δ	201.27, 156.37, 156.08, 143.99, 143.78, 141.49 (2×C), 127.88, 127.23, 125.25, 120.14, 67.20, 61.50, 61.10, 60.55, 47.36, 40.05, 32.02, 29.66, 28.55, 26.36, 21.20, 14.34
HRMS (ESI), C₃₃H₄₈N₂O₆SSi, m/z	[M+Na]⁺ theoretical 651.2895, observed 651.2895, mass accuracy 0.07 ppm; [M+K]⁺ theoretical 667.2634, observed 667.2648, mass accuracy 2.11 ppm

S-(2-((tert-butyldimethylsilyl)oxy)ethyl)-(S)-2-((((9H-fluoren-9-yl)methoxy) carbonyl)amino)-6-((tert-butoxycarbonyl)amino)hexanethioate
Identifier	Compound 12
¹H NMR (300 MHz, CDCl₃), δ	7.78 (pseudo-d, J = 7.5 Hz, 2H), 7.70-7.58 (m, 2H), 7.40 (pseudo-d, J = 7.6 Hz, 2H), 7.31 (pseudo-d, J = 7.6 Hz, 2H), 5.48 (bd, J = 8.4 Hz, 1H) 4.78–4.43 (m, 4H), 4.23 (t, J = 7.0 Hz, 1H), 3.70 (t, 2H), 3.18 – 3.10 (m, 4H), 3.06 (t, J = 6.9 Hz, 2H), 1.94 – 1.86 (m, 1H), 1.73 – 1.60 (m, 1H), 1.55 – 1.31 (m, 4H), 1.43 (s, 9H), 0.88 (s, 9H), 0.05 (s, 6H)
¹³C{¹H} NMR (76 MHz, CDCl₃), δ	200.90, 156.32, 156.05, 144.01, 143.80, 141.43, 127.84, 127.21, 125.24, 120.10, 67.24, 61.89, 61.00, 47.32, 39.94, 32.38, 31.70, 29.82, 28.55, 25.97, 22.46, 18.39, −5.18
HRMS (ESI), C₃₃H₄₈N₂O₆SSi, m/z	[M+Na]⁺ theoretical 651.2895, observed 651.2895, mass accuracy 0.07 ppm; [M+K]⁺ theoretical 667.2634, observed 667.2648, mass accuracy 2.11 ppm; the source prints this C₃₃H₄₈N₂O₆SSi formula/adduct block under Compound 12 even though it duplicates Compound 11’s complete HRMS block, and it is retained without resolving the inconsistency
HRMS (ESI), C₃₄H₅₀N₂O₆SSi, m/z	[M+Na]⁺ theoretical 665.3051, observed 665.3062, mass accuracy 1.64 ppm; [M+K]⁺ theoretical 681.279, observed 681.2791, mass accuracy 0.08 ppm

N-(((9H-fluoren-9-yl)methoxy)carbonyl)-S-(N²-(((9H-fluoren-9-yl)methoxy)carbonyl)-N⁶-(tert-butoxycarbonyl)-L-lysyl)-L-cysteine
Identifier	Compound 13
¹H NMR (300 MHz, CDCl₃), δ	7.77 (pseudo-d, J = 7.5 Hz, 4H), 7.57 (pseudo-d, J = 7.4 Hz, 4H), 7.41 (pseudo-t, J = 7.4 Hz, 4H), 7.32 (pseudo-t, J = 7.5 Hz, 4H), 5.49 (bs, 3H), 5.30 (s, 1H), 4.47 (bd, J = 6.7 Hz, 2H), 4.23 (d, J = 6.6 Hz, 2H), 4.12 (d, J = 7.1 Hz, 2H), 3.54 – 3.39 (bt, J = 7.1 Hz, 2H), 3.36–3.25 (m, 2H), 2.00–1.87 (m, 1H), 1.79–1.40 (m, 5H), 1.59 (s, 9H)
¹³C{¹H} NMR (126 MHz, C₆D₆), δ	143.64, 141.49, 127.98, 127.28, 125.07, 120.21, 72.28, 67.56, 47.18, 29.85, 27.74
HRMS (ESI), C₄₄H₄₇N₃O₉S, m/z	[M+H]⁺ theoretical 794.3106, observed 794.3095, mass accuracy 1.36 ppm; [M+Na]⁺ theoretical 816.2925, observed 816.2915, mass accuracy 1.25 ppm

Methyl N-(((9H-fluoren-9-yl)methoxy)carbonyl)-S-(N²-(((9H-fluoren-9-yl)methoxy)carbonyl)-N⁶-(tert-butoxycarbonyl)-L-lysyl)-L-cysteinate
Identifier	Compound 14
¹H NMR (300 MHz, CDCl₃), δ	7.75 (pseudo-d, J = 7.5 Hz, 4H), 7.60 (pseudo-d, J = 6.9 Hz, 4H), 7.39 (pseudo-t, J = 7.4 Hz, 4H), 7.34 – 7.27 (m, 4H), 5.64 (d, J = 7.9 Hz, 1H), 5.57-5.46 (m, 1H), 4.70 – 4.48 (m, 1H), 4.54 (dd, J = 10.2, 7.8 Hz, 1H), 4.34 (d, J = 10.1 Hz, 2H), 4.23 (bt, J = 6.1 Hz, 2H), 3.70 (s, 1H), 3.46 (dd, J = 14.2, 4.0 Hz, 1H), 3.33 (dd, J = 14.2, 6.2 Hz, 1H), 3.15-3.00 (m, 2H), 1.88 – 1.74 (m, 2H), 1.73 – 1.53 (m, 2H), 1.54–1.33 (m, 2H), 1.43 (s, 9H)
¹³C{¹H} NMR (126 MHz, CDCl₃), δ	200.98, 170.87, 156.68, 156.44, 156.05, 144.21, 144.11, 143.97, 141.67, 141.62, 128.09, 127.46, 125.56, 125.49, 125.43, 120.35, 79.65, 67.59, 67.52, 61.44, 53.88, 53.81, 53.19, 47.52, 47.43, 39.94, 32.02, 31.08, 29.99, 28.78, 22.58
HRMS (ESI), C₄₅H₄₉N₃O₉S, m/z	[M+H]⁺ theoretical 808.3262, observed 808.3262, mass accuracy 0.03 ppm; [M+Na]⁺ theoretical 830.3082, observed 830.3078, mass accuracy 0.45 ppm; [M+K]⁺ theoretical 846.2821, observed 846.2806, mass accuracy 1.78 ppm

S-octyl (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)-hexanethioate
Identifier	Compound 15
¹H NMR (300 MHz, CDCl₃), δ	7.77 (pseudo-d, J = 7.5 Hz, 2H), 7.63 (pseudo-t, J = 6.1 Hz, 2H), 7.41 (pseudo-t, J = 7.5 Hz, 2H), 7.32 (pseudo-t, J = 7.4 Hz, 2H), 5.43 (d, J = 6.6 Hz, 1H), 4.65-4.53 (m, 1H), 4.51 (dd, J = 10.0, 6.1 Hz, 1H), 4.46 – 4.31 (m, 2H), 4.24 (t, J = 6.8 Hz, 1H), 3.16 – 3.05 (m, 2H), 2.87 (t, J = 7.1 Hz, 2H), 1.95–1.82 (m, 1H), 1.44 (s, 9H), 1.75-1.20 (m, 17H), 0.87 (t, J = 6.7 Hz, 3H)
¹³C{¹H} NMR (126 MHz, CDCl₃), δ	201.09, 156.30, 156.08, 144.06, 143.85, 141.47, 127.86, 127.22, 125.27, 120.12, 79.41, 67.24, 61.00, 47.36, 40.01, 31.91, 29.85, 29.43, 29.27, 29.19, 29.05, 29.01, 28.57, 22.76, 22.47, 14.23
HRMS (ESI), C₃₄H₄₈N₂O₅S, m/z	[M+Na]⁺ theoretical 619.3176, observed 619.3181, mass accuracy 0.78 ppm; [M+K]⁺ theoretical 635.2916, observed 635.2914, mass accuracy 0.24 ppm

S-benzyl (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)-hexanethioate
Identifier	Compound 16
¹H NMR (300 MHz, CDCl₃), δ	7.74 (pseudo-d, J = 7.5 Hz, 2H), 7.60 (pseudo-d, J = 7.1 Hz, 2H), 7.44 – 7.32 (pseudo-t, J = 6.9 Hz, 2H), 7.34-7.12 (m, 7H), 5.55 (bd, J = 6.5 Hz, 1H), 4.59 (bs, 1H), 4.48 (dd, J = 16.4, 9.5 Hz, 1H), 4.47–4.31 (m, 2H), 4.22 (dd, J = 4.2, 4.3 Hz, 1H), 4.15–4.02 (m, 2H), 3.07 (d, J = 3.4 Hz, 2H), 1.97–1.77 (m, 1H), 1.76–1.57 (m, 1H), 1.52–1.30 (m, 4H), 1.43 (s, 9H)
¹³C{¹H} NMR (126 MHz, CDCl₃), δ	200.80, 156.57, 144.19, 144.07, 141.69, 137.32, 129.26, 129.03, 128.09, 127.77, 127.46, 125.49, 125.47, 120.35, 79.65, 67.47, 61.16, 47.57, 40.18, 33.68, 32.52, 30.05, 28.81, 22.66
HRMS (ESI), C₃₃H₃₈N₂O₅S, m/z	[M+Na]⁺ theoretical 597.2394, observed 597.2401, mass accuracy 1.23 ppm; [M+K]⁺ theoretical 613.2133, observed 613.2130, mass accuracy 0.49 ppm

S-phenyl (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-6-((tert-butoxycarbonyl)amino)-hexanethioate
Identifier	Compound 17
¹H NMR (301 MHz, CDCl₃), δ	7.76 (d, 2H), 7.64 (d, 2H), 7.50 – 7.32 (m, 6H), 7.36 – 7.28 (m, 3H), 4.54 (d, 2H), 4.40 (t, 2H), 3.14 (t, 2H), 2.00 – 1.92 (m, 2H), 1.79 – 1.68 (m, 2H), 1.45 (s, 9H), 1.29 – 1.23 (m, 2H)
¹³C{¹H} NMR (126 MHz, CDCl₃), δ	199.33, 156.37, 156.12, 143.96, 143.82, 141.48, 134.80, 129.69, 129.40, 129.20, 127.88, 127.65, 127.29, 127.25, 127.12, 125.25, 120.13, 67.30, 60.93, 47.36, 39.91, 32.22, 29.86, 28.57, 22.46
HRMS (ESI), C₃₂H₃₆N₂O₅S, m/z	[M+H]⁺ theoretical 583.2237, observed 583.2242, mass accuracy 0.83 ppm; [M+Na]⁺ theoretical 599.1977, observed 599.1970, mass accuracy 1.09 ppm