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Diver, S. T., Science of Synthesis, (2009) 46, 121.
The cross enyne metathesis between alkynes and ethene is an effective way to synthesize substituted buta-1,3-dienes. Using an atmosphere of ethene gas supplied through a balloon, an effective cross metathesis with a variety of terminal and internal alkynes has been demonstrated[25] (see also Section 46.3.1.1). These early studies utilized the first-generation Grubbs catalyst 1 (see Scheme 3) and required extended reaction times. The procedure produces 2-substituted buta-1,3-dienes from terminal alkynes and 2,3-disubstituted buta-1,3-dienes from internal alkynes (Scheme 37). The cross metathesis has seen many more examples of terminal alkyne reactions than that of internal alkynes, although each class of alkyne appears to be reactive. Even though the intramolecular ring-closing metathesis with Grubbs’ carbenes demonstrates excellent functional-group tolerance, intermolecular reactions are more demanding. In general, cross-metathesis reactions are more sensitive to functional groups, particularly strongly coordinating groups such as alkyl ethers. If the heteroatom functionality is more remote or if the Lewis basic nature of the heteroatom is attenuated, then the reaction is fairly reliable. Nonetheless, the nature of the bimolecular reaction reveals some limitations for certain substrates, thought to arise from chelate stabilization of reactive intermediates.
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Meeeee 88 Meeeee–Meeeee Meeee Meeeeeeeee[88]
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Meeeee 88 Meee-8,8-eeeeee Meeeeeeeeee ee Meeeee Meeeee Meeeeeee[88]
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Meeeee 88 Meeeeeee ee Meeeeeee Meeee Meeee Meeeee’ Meeeee-Meeeeeeeee Meeeeee[88]
Meeeee–eeeeee eeeeeeeeee eee eeee eeee ee eeeeeee eeeeeee eeeeeeeee. Meee, eeeeeeeee ee eeeeeeee eeeee ee eeeeee eeeeeeeeee eeee eee eeeeee-eeeeeeeeee Meeeee eeeeeee eeeeeeeee ee e eeeeee eeeeeeeeeee (Meeeee 88).[88]
Meeeee 88 Meeeeeeee Meeeeeee ee Meeeeeeee ee Meeeee–Meeeee Meeee Meeeeeeeee[88]
M eeeeee eeeeeeeeee eeeeee eeeeeeeeee ee eee eeeeeee 88 eeeee e 8,8-eeeeeeeeeeeee eeee-8,8-eeeee eeeeeeee ee eee eeeeeeeeeee eeeeeeeee ee eeeeeeeeeeeee M (Meeeee 88).[888]
Meeeee 88 Meeeeeeee Meeeeeee ee Meeeeeeeeeeee ee Meeeee–Meeeee Meeee Meeeeeeeee[888]
Mee eeeeeeeeee eeee eee Meeeee eeeeeeee, eeeeee eeeeeeeeeeeee ee eee eeeeeeeeeee eeeeeeee eee eeeeeeeee e eeeeeeeeee. Mee eeeeeeee ee eeeeee eee eeee eeeeeeeeee eeeeee ee eeee eeeee. Meeeeeeeeee, eeeeee eeeeeeeee eee eeeee eeeeeee eee eeeeee eeeeeee ee eeeeee (eee Meeeee 88). Meee eeeeeeeeee eeeeee eeee eee eeeeeeeeee eeeeeee eeeeeeeee (e.e., eeee eeeeeeeee). Me eeeee eeeeeeeeee, eeeeeeee 88 (M8 = eeeee) eeee eeee eeeee eeeeeeeeee eeeeeee eeeee eeeeee 88 (M8 = eeee) eee ee eeee eeeeeeeeeeee ee eeee 8,8-eeeeee 88 (Meeeee 88).[888]
Meeeee 88 Meeeee Meeeeeeeeeeee ee Meeeee–Meeeee Meeee Meeeeeeeee[888]
M8 | M8 | Meeeee | Meeeeeeeeee (%) | Meeeee (%) | Mee |
---|---|---|---|---|---|
Me | M | M | 8 | e.e. | [888] |
Me | M | M | 88 | 88 | [888] |
Me | Me | M | 88 | 88 | [888] |
Me | Me | M | 88 | e.e. | [888] |
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Meeee ee eee eeeee eeeeee ee eee eeeeeeee eeeee ee eeeee eeeeee, eee eeeeee eeee eeee ee eeee Meeee eeeee. Meee eeeee eeeeee eeeeeeee eeeeee. Meeee eeeeeeee (eeeeeeeeeeeeee) eee eeeee eeeeeeeee (eeeeeeeeeeeeeeeeeeee) eeee eeee eee eee eeeeeeeeeeee eeeeeeee ee Meeeeeeee eeeeeeee ee eee eeeeeeeeeeeee eeeeeeee. Mee eee eeeee eeeeeeee 88 (M8 = Me; M8 = Me) ee eee ee eeee eeee eee eeeee-eeeeeeeeee eeeeeee 8 eee eee eeeeeee ee eeee ee eee eeeeee-eeeeeeeeee eeeeeee 8.
Me eeeeeee, eeee eeeee- eee eeeeee-eeeeeeeeee Meeeee eeeeeeeee eee ee eeee ee eeeeee–eeeeee eeeee eeeeeeeeee. Mee eeee eeeeeeeee eeeee, eeee ee eeeee eeee α-eeeeeeeee ee eee eeeeeeeeeee eeeeeeee ee eeeee eeeeeee eeeeeee eeee eeeeee-eeeeeeeeee eeeeeeeeeeeee (eeee ee eeeee eeeeee), eee eeeeeeeee eeeeeee eeee eeeeee eeeeee eeeeeeee. Meeee eee eeee eeeeeeeeeeee ee eee eeeeee-eeeeeeeeee Meeeee eeeeeee, ee ee eeeeeeeee ee eeeeee eeee eeeeeeee ee eeeeeeeeeee eeee eeeeeeee eeeeeeee eeeeee eeeeeeeee ee eee eeeee eeeeeeeeee ee eeeeeeeee.
References
[2] | Meeee, M. M.; Meeeeeee, M. M.; Meeeeee, M. M.; Meeee, M. M., M. Me. Meee. Mee., (8888) 888, 8888. |
[25] | Meee, M.; Meeeeeeeee, M.; Meeeeeeee, M., M. Mee. Meee., (8888) 88, 8888. |
[26] | Meeeeeeee, M.; Meeeeeeeee, M.; Meee, M., M. Me. Meee. Mee., (8888) 888, 88888. |
[97] | Meeeee, M. M.; Meeee, M. M., M. Mee. Meee., (8888) 88, 8888. |
[98] | Meeeee, M. M.; Meeee, M. M., Mee. Meee., (8888) 8, 8888. |
[99] | Meee, M.; Meeeeeee, M.; Meeeeeeeee, M., M. Mee. Meee., (8888) 88, 888. |
[100] | Müeeeeee, M.; Meeeeeee, M.; Meüeee, M., Meeee. Meee., (8888) 888, 8888; Meeee. Meee. Mee. Me., (8888) 88, 8888. |
[101] | Meeeee, M. M.; Meeeeeee, M. M.; Meeee, M. M., Meeeeeeeeee Meee., (8888) 88, 888. |