Triphenylphosphine → (R)-methyl 2-(tert-butoxycarbonylamino)-2-(2-oxoethyl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate

HRID 579480Notes

Reaction equation

HRID 579480 reaction equation
[CH2:1]([C@:4]([NH:22][C:23]([O:25][C:26]([CH3:29])([CH3:28])[CH3:27])=[O:24])([CH2:9][CH2:10][CH2:11][CH2:12][B:13]1[O:17][C:16]([CH3:19])([CH3:18])[C:15]([CH3:21])([CH3:20])[O:14]1)[C:5]([O:7][CH3:8])=[O:6])[CH:2]=C.[O:30]=[O+][O-].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>ClCCl>[C:26]([O:25][C:23]([NH:22][C@@:4]([CH2:1][CH:2]=[O:30])([CH2:9][CH2:10][CH2:11][CH2:12][B:13]1[O:14][C:15]([CH3:20])([CH3:21])[C:16]([CH3:18])([CH3:19])[O:17]1)[C:5]([O:7][CH3:8])=[O:6])=[O:24])([CH3:29])([CH3:28])[CH3:27]

Participants

5

Reactant 3

HCID 11776TriphenylphosphineHCID 24823Ozone2×HCID 66833177(R)-methyl 2-allyl-2-(tert-butoxycarbonylamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate

Product 1

HCID 71600280(R)-methyl 2-(tert-butoxycarbonylamino)-2-(2-oxoethyl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoateYield 67%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of (R)-methyl 2-allyl-2-(tert-butoxycarbonylamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate (1.90 g, 4.62 mmol) in dichloromethane (90 mL, 0.05 M) was cooled to −78° C. and treated with ozone until a pale blue-gray color appeared. After TLC indicated the absence of starting material, the ozone inlet tube was replaced with nitrogen and nitrogen was bubbled through the solution for 20 min to remove any excess ozone. Triphenylphosphine (3.6 g, 13.8 mmol, 3 equiv) was added in one portion, the cooling bath was removed and the mixture was stirred for 4 h. The solution was concentrated and purified by MPLC (1-50% ethyl acetate in heptane over 6 CV) and gave (R)-methyl 2-(tert-butoxycarbonylamino)-2-(2-oxoethyl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate as a colorless oil (1.28 g, 67%). Rf 0.55 (30% ethyl acetate in heptane); 1H NMR (CDCl3, 300 MHz) δ 9.66 (s, 1H), 5.62 (br s, 1H), 3.75 (s, 3H), 3.60 (br d, J=17.4 Hz, 1H), 2.95 (d, J=17.4 Hz, 1H), 2.30-2.15 (m, 1H), 1.70-1.54 (m, 1H), 1.40 (s, 9H), 1.39-1.24 (m, 4H), 0.74 (t, J=7.8 Hz, 2H); ESI-LCMS m/z calcd for C20H36BNO7: expected 413.3. found 414.3 (M+H)+.

Workup

  1. customwas bubbled through the solution for 20 min
  2. customto remove any excess ozone
  3. customthe cooling bath was removed
  4. concentrationThe solution was concentrated
  5. custompurified by MPLC (1-50% ethyl acetate in heptane over 6 CV)

Sources & evidence

ORD record
ord-3e44a1eef9a746d282a27c6d095adbf3
Source dataset
uspto-grants-2015_05
Patent number
US09040703B2

Reaction notes

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