Trifluoroacetic acid → 2-(4-Allylchroman-6-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

HRID 1400711Notes

Reaction equation

HRID 1400711 reaction equation
[CH2:1]([C:4]1(O)[C:13]2[C:8](=[CH:9][CH:10]=[C:11]([B:14]3[O:18][C:17]([CH3:20])([CH3:19])[C:16]([CH3:22])([CH3:21])[O:15]3)[CH:12]=2)[O:7][CH2:6][CH2:5]1)[CH:2]=[CH2:3].C([SiH](CC)CC)C.C(O)(C(F)(F)F)=O>ClCCCl>[CH2:1]([CH:4]1[C:13]2[C:8](=[CH:9][CH:10]=[C:11]([B:14]3[O:18][C:17]([CH3:20])([CH3:19])[C:16]([CH3:22])([CH3:21])[O:15]3)[CH:12]=2)[O:7][CH2:6][CH2:5]1)[CH:2]=[CH2:3]

Participants

5

Reactant 3

HCID 6422Trifluoroacetic acidHCID 12052TriethylsilaneHCID 867107644-Allyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)chroman-4-ol

Product 1

HCID 867107632-(4-Allylchroman-6-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneYield 55.2%

Reagents, catalysts & solvents 1

HCID 111,2-DichloroethaneSolvent

Procedure

A stirred solution of 4-allyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)chroman-4-ol (1.80 g, 5.69 mmol) and triethylsilane (7.27 ml, 45.5 mmol) in DCE (30 ml) was treated with TFA (14.03 ml, 182 mmol) by rapid addition at ambient temperature. The reaction was stirred for 10 min, then carefully quenched with sat'd. aq. NaHCO3 (200 mL). The organic layer was concentrated and the residue was purified by biotage (80 g SiO2, 0% (3 CV), 0-60% (15 CV), 60% (2 CV), EtOAc in hexanes) to afford the desired product (0.942 g, 3.14 mmol, 55.1% yield) as a viscous clear oil. 1H NMR (400 MHz, CDCl3) δ 7.64 (s, 1H), 7.56 (dd, J=8.2, 1.4 Hz, 1H), 6.80 (d, J=8.0 Hz, 1H), 5.90-5.76 (m, 1H), 5.15-5.04 (m, 2H), 4.23-4.14 (m, 2H), 2.89 (dq, J=10.0, 5.0 Hz, 1H), 2.75-2.62 (m, 1H), 2.35-2.22 (m, 1H), 2.09-1.96 (m, 1H), 1.92-1.81 (m, 1H), 1.34 (s, 12H). LCMS (M+H)=301.3.

Workup

  1. customcarefully quenched with sat'd
  2. concentrationThe organic layer was concentrated
  3. customthe residue was purified by biotage (80 g SiO2, 0% (3 CV), 0-60% (15 CV), 60% (2 CV), EtOAc in hexanes)

Sources & evidence

ORD record
ord-0de247cbe72f4f3a932c67fc32cdc245
Source dataset
uspto-grants-2014_12
Patent number
US08906929B2

Reaction notes

Loading…