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. 2019 Feb 1;75(5):580-583.
doi: 10.1016/j.tet.2018.12.039. Epub 2018 Dec 22.

Expanding the functional group tolerance of cross-coupling in 1,2-dihydro-1,2-azaborines: installation of alkyl, alkenyl, aryl, and heteroaryl substituents while maintaining a B-H bond

Alec N Brown  1 , Bo Li  1 , Shih-Yuan Liu  1
Affiliations

Expanding the functional group tolerance of cross-coupling in 1,2-dihydro-1,2-azaborines: installation of alkyl, alkenyl, aryl, and heteroaryl substituents while maintaining a B-H bond

Alec N Brown et al. Tetrahedron. .

Abstract

Palladium-catalyzed Negishi cross-coupling of 3-bromo-1-(tert-butyldimethylsilyl)-1,2-dihydro-1,2-azaborine while maintaining the B-H functionality has been demonstrated. 17 examples, including dialkylzinc, alkyl-, alkenyl-, aryl-, as well as nitrogen-, sulfur-, and oxygen-containing heteroaryl-zinc halide reagents have been coupled to generate new C(3) substituted 1,2-azaborines in moderate to excellent yields.

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Figures

Figure 1:
Figure 1:
N-TBS,B–Cl-1,2-Azaborine 1
Figure 2.
Figure 2.
ORTEP illustration, with thermal ellipsoids drawn at the 35% probability level of 4l; all hydrogen atoms (except of the B-H) have been omitted for clarity.
Scheme 1:
Scheme 1:
Cross-coupling strategies for carbon-carbon bond formation in BN-arenes.
Scheme 2:
Scheme 2:. Negishi cross-coupling of 3 with alkyl- and dialkyl- zinc reagents.
Percent yields are isolated and the average of two runs. a Dialkylzinc (1.5 equiv) used bAlkylzinc bromide (1.5 equiv) used.
Scheme 3:
Scheme 3:. Negishi cross-coupling of 3 with aryl-, alkenyl-, and heteroaryl-, zinc halide reagents.
Percent yields are isolated and the average of two runs. a conditions: 3 equiv 2,4,6-trimethylphenylzinc iodide, 0.05 equiv Pd(PtBu3)2, THF, rt, 48 h. b4-bromophenylzinc iodide was used. c2,3-Methylenedioxyphenylzinc iodide was used.
See this image and copyright information in PMC

References

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