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Please login to access the full content or check if you have access via4.4.7.2.1.4 Variation 4: Palladium-Catalyzed (2 + 2 + 1) Cycloaddition with Silylenes
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Delvos, L. B.; Oestreich, M., Science of Synthesis Knowledge Updates, (2017) 1, 85.
Amino-substituted silylboronic ester 47 adds oxidatively to palladium complexes followed by β-elimination of the amino group and the boron subunit to generate a transition-metal-stabilized silylene (see Scheme 2, General Introduction).[57] This intermediate engages in formal (2 + 2 + 1) cycloadditions with terminal alkynes 46 to selectively yield 2,4-disubstituted siloles 48 rather than the 3,4-disubstituted regioisomers 49 (Scheme 27).[57] Phenylacetylene (46, R1 = Ph) and its functionalized derivatives react well in the presence of triphenylphosphine, whereas alkynes 46 with alkyl substituents require the use of bulky phosphine ligands such as 34 and 45. The study also includes one example with [(diethylamino)diphenylsilyl]pinacolborane.[57]
Meeeee 88 Meeeeeeeeeeeee (8 + 8 + 8) Meeeeeeeeeeee ee Meeeeeee Meeeeee eeee e Meeeeeeee-Meeeeeeeee Meeeeeee[88]
| M8 | Meeeee | Meeee (88/88) | Meeee (%) | Mee |
|---|---|---|---|---|
| Me | Me8M | 88:8 | 88 | [88] |
| 8-MeMM8M8 | Me8M | 88:8 | 88 | [88] |
| 8-Me8MM8M8 | Me8M | 88:88 | 88e | [88] |
| 8-M8MM8M8 | Me8M | 88:8 | 88 | [88] |
| Mee | Me8M | 88:8 | 88 | [88] |
| 8-eeeeeeee | Me8M | 88:8 | 88 | [88] |
| (MM8)8Me | 88 | 88:88 | 88 | [88] |
| (MM8)8Me | 88 | 88:8 | 88 | [88] |
| (MM8)8MMMMMM | 88 | 88:8 | 88 | [88] |
| (MM8)8Me | 88 | 88:8 | 88 | [88] |
e 8M MMM eeeee.
Meeeeeeeeeee Meeeeeeee
8,8-Meeeeee-8,8-eeeeeeee-8M-eeeeee [88, M8 = (MM8)8Me]; Meeeeee Meeeeeeee:[88]
Meeeee 88 (8.8 ee, 8.8 µeee, 8.8 eee%) eee Me(eee)8 (8.8 ee, 8.8 µeee, 8.8 eee%) eeee eeeeeeeee ee eeeeeee (888 µM) ee e eeeee-eeeeee eeee, eee eee eeeeeeeee eeeeeee eee eeeeeee ee ee eee 8 eee. Mee-8-eee [88, M8 = (MM8)8Me; 8.88 e, 8.88 eeee, 8.8 eeeee] eee 8-[(eeeeeeeeeeee)eeeeeeeeeeeee]-8,8,8,8-eeeeeeeeeee-8,8,8-eeeeeeeeeeeee (88; 8.88 e, 8.88 eeee, 8.8 eeeee) eeee eeeee ee eeee eeeee, eee eeee eee eeeeeeeee eeeeeee eee eeeeeee ee ee. Meeeeeeeee eee eeeeeeeee ee MMM eeeeeeee. Meeee eee eeeeeeee eee eeeeeeee (88 e), eee eeeeeeeee eeee eeeeeeeeee. 8M MMM eeeeeeeeeeeee eeeeeeee ee eee eeeee eeeeeeee eeeeeeeee e 88:88 eeeee ee eeeeeeeeeeee 88 eee 88 [M8 = (MM8)8Me]. Mee eeeee eeeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee); eeeee: 88 ee (88%).
References
| [57] | Meeeee, M.; Meeeee, M.; Meeeeeee, M., M. Me. Meee. Mee., (8888) 888, 8888. |
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