4-Bromotoluene → Tolylboronic acid

HRID 1955585Notes

Reaction equation

HRID 1955585 reaction equation
[B:1]([C:4]1[CH:15]=[CH:14][C:7]([CH2:8][C@@H](C(O)=O)N)=[CH:6][CH:5]=1)([OH:3])[OH:2].BrC1C=CC(C)=CC=1.C(OB(OCC)OCC)C>>[B:1]([C:4]1[CH:15]=[CH:14][C:7]([CH3:8])=[CH:6][CH:5]=1)([OH:3])[OH:2]

Participants

4

Reactant 3

HCID 78054-BromotolueneHCID 9009Triethyl borateHCID 150315L-p-Boronophenylalanine

Product 1

HCID 79799Tolylboronic acid

Procedure

p-Boronophenylalanine can be synthesized by the scheme illustrated in FIG. 5D. Accordingly, from p-bromotoluene 81 by Grignard reaction and treatment with triethylborate at -78° C. followed by hydrolysis gave p-boronotoluene 82. This on bromination and oxidation gave 84 according to Snyder et al. (1958) J Am Chem Soc 80:835-838. Further treatment with N-methyldiethanolamine in THF afforded the cyclic boronate, which on reaction with ethylisocyanate and sodium hydride at -70°-20° C. gave (Z)-ethyl α-formyl cinnamate derivative 86. Catalytic hydrogenation of 86 gave boronophenylalanine ethyl ester derivative 87. Finally, 87 was treated with sodium hydroxide and HCl in one pot to afford boronophenylalanine.

Workup

  1. customfollowed by hydrolysis

Sources & evidence

ORD record
ord-3932d0cebd4e4b85b2b2a3598a30c437
Source dataset
uspto-grants-1998_07
Patent number
US05776902

Reaction notes

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