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

HRID 1778588Notes

Reaction equation

HRID 1778588 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) 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-74edeec58f404d11a245fb7c9ae691dd
Source dataset
uspto-grants-2016_02
Patent number
US09266908B2

Reaction notes

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