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Delvos, L. B.; Oestreich, M., Science of Synthesis Knowledge Updates, (2017) 1, 142.
A recent report demonstrated that ynoates 208 react with silylboronic ester 19 in the presence of tributylphosphine as organocatalyst in a fundamentally different silaboration reaction to form trans-difunctionalized enoates 209 as single stereoisomers (Scheme 85).[114] Here, the Si—C bond formation occurs exclusively α to the carboxy group, and the boronic ester subunit is attached to the β-position of the triple bond. A variety of functionalized aryl and alkyl substituents at the β-carbon atom are tolerated, demonstrating broad functional-group tolerance. The target compounds are formed in good to excellent yields from equimolar amounts of acceptor and silicon pronucleophile.
Meeeee 88 Meeeeeeee-Meeeeeeee eeee-Meeeeeeee Meeeeeeeeeee ee Meeeeee[888]
M8 | Meeee (%) | Mee |
---|---|---|
8-MeM8M8 | 88 | [888] |
8-MeMM8M8 | 88 | [888] |
8-Me8M(MM8)8MM8M8 | 88e | [888] |
8-MM8M8 | 88 | [888] |
Me | 88 | [888] |
Me | 88 | [888] |
(MM8)8MMMM | 88 | [888] |
(MM8)8MMMMMM | 88 | [888] |
eeeeeeeeeee | 88 | [888] |
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Meeeeeeeeeee Meeeeeeee
Meeee (M)-8-[Meeeeeee(eeeeee)eeeee]-8-(8-eeeeeeeeeeeee)-8-(8,8,8,8-eeeeeeeeeee-8,8,8-eeeeeeeeeeee-8-ee)eeeeeeee (888, M8 = 8-MeMM8M8); Meeeeee Meeeeeeee:[888]
8-[Meeeeeee(eeeeee)eeeee]-8,8,8,8-eeeeeeeeeee-8,8,8-eeeeeeeeeeeee (88; 88 ee, 8.88 eeee, 8.8 eeeee) eee eeeee 8-(8-eeeeeeeeeeeee)eeeeeeeeee (888, M8 = 8-MeMM8M8; 88 ee, 8.88 eeee, 8.8 eeeee) eeee eeeeee ee e eeee eeeeeeeeee e eeeeeeee eeeeeee eee. Mee eeee eee eeeeee eeee e Meeeee-eeeeee eeeeeee eeeeee eeeeee, eeeeeeeee, eee eeeeeeeeee eeee eeeee. Me8M (8.8 μM, 88 µeee, 88 eee%) eee eeeee ee eee eeee. Mee eeeeeee eee eeeeeee ee 88 °M eee 8 e, eeeeee, eee eeeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, eeeeee/MeMMe 88:8 ee 8:8); eeeee: 888 ee (88%).
References
[114] | Meeee, M.; Meeeee, M.; Meeeeeee, M., Mee. Meee., (8888) 88, 8888. |