1,2-Metallate Rearrangements of α-Alkoxyalkyl Cuprates

Abstract

α-Alkoxylalkyl cuprates undergo 1,2-metallate rearrangement to give secondary alkyl cuprates.

Key words

1,2-metallate rearrangement - glycosyl cuprates - alkyl­ation - α-alkoxyalkyl cuprates

References

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• 2 Kocienski PJ. In Organic Synthesis via Organometallics   Enders D. Gais H.-J. Keim W. Verlag Vieweg; Wiesbaden: 1993.  p.203-223  
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• 11 Compounds 14a and 14b were prepared the same way as the corresponding tribenzyl derivatives: Christopher JA. Kocienski PJ. Procter MJ. Synlett  1998,  425 
• 13 Although the reaction of organocuprates with alkyl iodides may involve the formation of radicals, tosylates are considered to react strictly according to an S_N2 mechanism: Alkylations of Nonstabilised Carbanions; Klunder JM. Posner GH. Comprehensive Organic Synthesis   Vol. 3:  Trost BM. Fleming I. Pergamon Press; Oxford: 1991.  p.207 
• 14 The β-2-deoxyglucosylcopper(I) reagent is configurationally stable at 0 °C but the α-2-deoxyglucosyl-copper(I) rearranges to the β-anomer at 0 °C: Hutchinson DK. Fuchs PL. J. Am. Chem. Soc.  1987,  109:  4930 
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8

We coined the term 1,2-metallate rearrangement to describe a large class of reactions involving nucleophlic displacement reactions of electrophilic carbenoids (see ref. 1).

12

Compounds 17a and 17b were converted into the corresponding methyl ethers 18a and 18b and their structures determined by stereoselective synthesis.

27

Selected Spectroscopic Data for Compounds 7, 11, 13, 18a and 18b: Compound 7: IR (neat): 3334, 3076, 2956, 2927, 2860, 1639, 1589, 1456 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 5.78 (1 H, ddt, J = 16.7, 9.8, 7.3 Hz, H₂C=CH), 5.05-4.97 (2 H, m, H ₂C=CH), 3.64 (2 H, q, J = 6.4 Hz, CH ₂OH), 2.10-2.00 (2 H, m, CH ₂CH=CH₂), 1.61-1.53 (2 H, m, C2H₂), 1.46-1.38 (1 H, m, C4H), 1.35-1.21 (9 H, m, OH, 4 × CH₂), 0.90 (3 H, t, J = 6.8 Hz, CH₃). ¹³C NMR (75 MHz, CDCl₃): δ = 137.5 (H₂C=CH), 115.9 (H₂ C=CH), 63.5 (C1H₂), 38.2 (CH₂CH=CH₂), 37.3 (C4H), 33.1 (CH₂CH₂CH₂CH₃), 30.1 (C2H₂), 29.4 (C3H₂), 29.0 (CH₂CH₂CH₃), 23.2 (CH₂CH₃), 14.3 (CH₃). HRMS (ES): m/z calcd for C₁₁H₂₃O [M + H]⁺: 171.1749. Found: 171.1751.
Compound 11: IR (neat): 3336, 3076, 2927, 2859, 1640, 1458 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 5.77 (1 H, ddt, J = 17.1, 10.3, 7.0 Hz, H₂C=CH), 5.03-4.96 (2 H, m, H ₂C=CH), 3.64 (2 H, t, J = 6.5 Hz, CH ₂OH), 2.03 (2 H, t, J = 6.0 Hz, CH ₂CH=CH₂), 1.55 (2 H, app quintet, J = 6.5 Hz, C2H₂), 1.46-1.20 (12 H, m, OH, C5H, 5 × CH₂), 0.89 (3 H, t, J = 6.5 Hz, CH₃). ¹³C NMR (75 MHz, CDCl₃): δ = 137.7 (H₂C=CH), 115.8 (H₂ C=CH), 63.2 (C1H₂), 38.2 (CH₂CH=CH₂), 37.5 (C5H), 33.3 (CH₂), 33.3 (CH₂), 33.2 (CH₂), 29.1 (CH₂CH₂CH₃), 23.2 (CH₂), 23.0 (CH₂), 14.3 (CH₃). HRMS (ES): m/z calcd for C₁₂H₂₄ONa [M + Na]⁺: 207.1725. Found: 207.1719.
Compound 13: IR (neat): 3075, 2928, 2858, 1639, 1589, 1508 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 6.40 (2 H, s, 2 ArH), 5.80 (1 H, ddt, J = 17.1, 10.3, 6.8 Hz, H₂C=CH), 4.92-4.83 (2 H, m, H ₂C=CH), 3.86 (6 H, s, 2 m-CH₃O), 3.83 (3 H, s, p-CH₃O), 2.56 (2 H, dd, J = 9.4, 6.4 Hz, CH ₂Ar), 2.11 (2 H, t, J = 6.4 Hz, CH ₂CH=CH₂), 1.48-1.37 (2 H, m, CH ₂CH₂Ar), 1.35-1.26 (1 H, m, CH), 1.22-1.08 (6 H, m, 3 × CH₂), 0.91 (3 H, t, J = 6.8 Hz, CH₃). ¹³C NMR (75 MHz, CDCl₃): δ = 153.1 (2 COCH₃, Ar ring), 139.0 (C, Ar ring), 137.4 (H₂C=CH), 136.0 (COCH₃, Ar ring), 116.0 (H₂ C=CH), 105.2 (2 CH, Ar ring), 61.0 (CH₃O), 56.1 (2 CH₃O), 38.1 (CH₂CH=CH₂), 37.2 (CHCH₂CH=CH₂), 35.4 (CH₂CH₂Ar), 33.7 (CH₂Ar), 33.1 (CH₂CH₂CH₂CH₃), 29.0 (CH₂CH₂CH₃), 23.2 (CH₂CH₃), 14.3 (CH₃). HRMS (ES): m/z calcd for C₁₉H₃₁O₃ [M + H]⁺: 307.2273. Found: 307.2281.
Compound 18a: [α]_D +12.3 (c 0.70, CHCl₃). IR (neat): 2955, 2927, 2826, 1459, 1378, 1186, 1103 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 3.69 (1 H, dd, J = 10.7, 2.6 Hz, C1H _AH_B), 3.50 (1 H, dd, J = 10.9, 3.6 Hz, C1H_A H _B), 3.50-3.36 (2 H, m, C2H and C4H), 3.46 (3 H, s, CH₃O), 3.42 (3 H, s, CH₃O), 3.40 (3 H, s, CH₃O), 3.39 (3 H, s, CH₃O), 3.24 (1 H, dd, J = 7.7, 3.0 Hz, C3H), 1.65 (1 H, ddd, J = 13.3, 7.7, 6.0 Hz, C5H _AH_B), 1.62-1.53 (1 H, m, C6H), 1.37-1.10 (7 H, m, C5H_A H _B and 3 × CH₂), 0.92 (3 H, d, J = 6.4 Hz, CH ₃C6H), 0.89 (3 H, t, J = 6.4 Hz, C10H₃). ¹³C NMR (75 MHz, CDCl₃): δ = 81.7 (C3H), 79.8 (C2H), 78.4 (C4H), 70.3 (C1H₂), 61.0 (CH₃O), 59.2 (CH₃O), 58.8 (CH₃O), 57.5 (CH₃O), 38.5 (C5H₂), 37.3 (C7H₂), 29.5 (C6H), 29.3 (C8H₂), 23.2 (C9H₂), 20.1 (CH₃C6H), 14.3 (C10H₃). HRMS (ES): m/z calcd for C₁₅H₃₂O₄Na [M + Na]⁺: 299.2198. Found: 299.2190.
Compound 18b: IR (neat): 2955, 2927, 2826, 1462, 1377, 1186, 1103 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 3.72 (1 H, dd, J = 10.3, 2.1 Hz, C1H _AH_B), 3.51 (1 H, dd, J = 10.7, 3.4 Hz, C1H_A H _B), 3.49-3.36 (2 H, m, C2H and C4H), 3.46 (3 H, s, CH₃O), 3.42 (3 H, s, CH₃O), 3.40 (3 H, s, CH₃O), 3.37 (3 H, s, CH₃O), 3.26 (1 H, dd, J = 7.7, 2.1 Hz, C3H), 1.59 (1 H, ddd, J = 13.3, 8.1, 4.7 Hz, C5H _AH_B), 1.57-1.46 (1 H, m, C6H), 1.42 (1 H, ddd, J = 13.7, 8.5, 6.0 Hz, C5H_A H _B), 1.39-1.13 (6 H, m, 3 × CH₂), 0.91 (3 H, d, J = 6.4 Hz, CH ₃C6H), 0.89 (3 H, t, J = 6.8 Hz, C10H₃). ¹³C NMR (75 MHz, CDCl₃): δ = 80.3 (C3H), 79.6 (C2H), 78.4 (C4H), 70.2 (C1H₂), 61.0 (CH₃O), 59.2 (CH₃O), 58.0 (CH₃O), 57.6 (CH₃O), 37.5 (C7H₂), 37.1 (C5H₂), 29.5 (C6H), 29.3 (C8H₂), 23.1 (C9H₂), 20.2 (CH₃C6H), 14.3 (C10H₃). HRMS (ES): m/z calcd for C₁₅H₃₂O₄Na [M + Na]⁺: 299.2198. Found: 299.2197.