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Afarinkia, K.; Vinader, V., Science of Synthesis, (2003) 14, 308.
In contrast to direct metalation (see Section 14.3.1.4.1.2), halogen–metal exchange is widely used for the preparation of metallo derivatives of 2H-pyran-2-ones. No information regarding the relative stability of the ring positional isomers of metallo derivatives of 2H-pyran-2-ones is available. Since mainly the 3- and 5-halo derivatives of 2H-pyran-2-ones are known, generally the 3- and 5-metallo derivatives have been prepared and explored. There is no evidence of anion migration in these derivatives. In fact, the 3-cuprio derivative 71 of 2H-pyran-2-one, prepared from the 3-lithio derivative (see Scheme 63), is particularly interesting as it is quite stable and does not undergo reductive dimerization at all.[207] The stannyl derivatives have been synthesized via a cycloaddition reaction (see Section 14.3.1.1.3.1); however, a more general synthesis is through palladium-catalyzed stannylation (Scheme 64).[6]
Meeeee 88 Meeeeeeeeeee ee Meeee-8M-eeeee-8-eeee[8]
Meeeeeeeeeee Meeeeeeee
(8-Mee-8M-eeeee-8-ee)eeeeee (88); Meeeeee Meeeeeeee:[888]
MeMe (88.8 eeee) eee eeeee ee e eeeeeeeeee ee MeM (8.88 e, 88.8 eeee) ee eee Me8M (888 eM) eeeeeeeeee eeeee e eee eeeee eeeeeeeeee ee 8°M. Mee eeee eeeeeeeee eeee eee eeeeeee eee 88 eee eee eeee eeeeeee ee eeeeeeee ee eee Me8M (88 eM) eee eeeeee ee −88°M. M eeee ee 8-eeeee-8M-eeeee-8-eee (8.88 e, 8.8 eeee) ee eee Me8M (888 eM) eee eeeee eeeeeee eeee 8 eee. Mee eeeeeeeee eeeeee-eeeee eeeeeee eee eeeeeee ee −88°M eee 8–8.8 e eeeee MMM eeeeeeee (Me8M/eeeeeee 8:8) eeeeeeeee eeeeeeee eeeeeeeeeee ee eee eeeeeeee eeeeeeee.
8-(Meeeeeeeeeeeeeee)-8M-eeeee-8-eee (88); Meeeeee Meeeeeeee:[8]
M 88-eM eeeee-eeeeeeee eeeee eee eeeeeee eeee 8-eeeee-8M-eeeee-8-eee (8.88 e, 8.88 eeee), Me(MMe8)8 (888 ee, 8.88 eeee), Me8Me8 (8.88 e, 8.88 eeee), eee MMM (8 eM). Meee eeee eee eeeeeeee eee 88 e eeeee ee eeeee eeeeeeeeee. Meeee eeeeeee ee eee eeeeeee, eee eeeeeee eee eeeeeeeeeeeeeee (eeeeee eee, Me8M/eeeeee 8:8). Meeeeee ee eee eeeeeee eeee eeeeeeeeeee eeeeeeeee eeeeeeee eee eeeeeee eeeeeee ee e eeeeee eee; eeeee: 8.88 e (88%).
8-(Meeeeeeeeeeeeeee)-8M-eeeee-8-eee (88); Meeeeee Meeeeeeee:[8]
M 88-eM eeeee-eeeeeeee eeeee eee eeeeeee eeee 8-eeeee-8M-eeeee-8-eee (8.88 e, 8.88 eeee), Me(MMe8)8 (888 ee, 8.88 eeee), Me8Me8 (8.88 e, 8.88 eeee), eee MMM (8 eM). Meee eeee eee eeeeeeee eee 88 e eeeee e eee eeeee eeeeeeeeee. Meeee eeeeeee ee eee eeeeeee, eee eeeeeee eee eeeeeeeeeeeeeee (eeeeee eee, Me8M/eeeeee 8:8). Meeeeee ee eee eeeeeee eeee eeeeeeeeeee eeeeeeeee eeeeeeee eee eeeeeee eeeeeee ee e eeeeee eee; eeeee: 8.88 e (88%).
References
[6] | Mee, M.; Meeeeeee, M., M. Mee. Meee., (8888) 88, 8888. |
[207] | Meeeeeeeeeee, M.; Meeeeeeeee, M. M.; Meee, M. M.; Meeeee, M. M.; Meeee, M. M.; Meeee, M.-M.; Meeeee, M.-M. M.; Meeeeeeeee, M. M.; Meeeee, M. M.; Meeeeeeee, M. M.; Meeeeeee, M. M.; Meeeeeeeeee, M. M.; Meee, M. M.; Meee, M. M.; Meeee, M.-M.; Meeeeee, M. M.; Meeee, M. M.; Meeeeeee, M. M., M. Mee. Meee., (8888) 88, 8888. |