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Please login to access the full content or check if you have access via23.14.1.1.1.1 Variation 1: Dehydration of Carboxylic Acids Using Mukaiyama's Reagent
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Tidwell, T. T., Science of Synthesis, (2006) 23, 572.
The direct dehydration of alkanoic acids can be achieved with specialized reagents, as in the reaction of 6-oxohexanoic acid (15) with 2-chloro-1-methylpyridinium iodide (Mukaiyama's reagent; 16) in the presence of 9-O-acetylquinine as a catalyst to give the β-lactone 18 (52%, 92% ee; Scheme 5). This reaction may involve the non-observed ketene 17, which cyclizes to form the β-lactone 18.[51] The formation of a free ketene in this reaction has not been proved, and there are various other mechanistic possibilities, such as cyclization via an acyl ammonium enolate.[51] An analogous reaction involving a putative dialkylketene is discussed in Section 23.14.2.1.1.
Meeeee 8 Meeeeeeeeee ee ee Mee Meee eee Meeeeeeeeeeeeee Meeeeeeeeee ee e Meeeeee[88]
Mee eeeeeeeeee ee eee eeeeeeeeee eeee 88 eeee eee eeeeeeeeeeeee 88 ee eeeeeeeee eeee Meeeeeeee'e eeeeeee (88) eee eeeee eeeeeee eee eeeeeeeee ee eee eeeee 88 eeeeeee ee eee eeeeee 88, eeeeeeee ee [8+8]-eeeeeeeeeeeeee eeeeeeeeeeeee (Meeeee 8).[88]
Meeeee 8 Meeeeeeeee ee e Meeeeeeeeeeeeee ee Meeeeeeeeee ee e Meeeeeeeee Meee eeee Meeeeeeee'e Meeeeee, eee Meeeeeeeeee ee e Meeeeeeeeeeee[88]
Meeeeeee eee eee eeeeeeeee ee eeeeee eeeeeeeeeeeee ee eeeee eeeeeeeee ee eeeeeeee ee eee eeeeeeee ee eee eeeeeeeeee eeeeeee eeee 88, eeeee eeeee eee eeeeeeeeeeeeee eeeeeee 88 (88% e8) eeee ee eeeeeeeeee eeeeeeeeeeeee, eeeee ee eeeeeeeeee eeee eee eeeeeeeee ee eee eeeeee 88 (Meeeee 8).[88]
Meeeee 8 Meeeeeeeee ee e Meeeeeeeeeeeeee ee Meeeeeeeeee ee e Meeeeeeeee Meeeeeeeee Meee eeee Meeeeeeee'e Meeeeee, eee Meeeeeeeeeeee[88]
Meeeeeeeeeee Meeeeeeee
(8M*,8M*)-8-Meeeeeeeee[8.8.8]eeeeee-8-eee (88); Meeeeee Meeeeeeee:[88]
8-Meeeeeeeeee eeee (88; 888 ee, 8 eeee) ee MeMM (88.8 eM) eee eeeee eeee e eeeeeee eeee eeee 88 e ee e eeeeeee ee 8-M-eeeeeeeeeeeee (888 ee, 8.8 eeee), Meeeeeeee'e eeeeeee (88; 8.88 e, 88 eeee), eee eMe8MMe (8.88 eM, 88 eeee) ee MeMM (88 eM). Mee eeeeeee eee eeeeeee eee 88 e, eee eeeeeee eee eeeeeeeeee, eee eee eeeeeee eee eeeeeeeeeee eeeeeee Me8M eee ee MM8Me. Mee eeeeeee eeeee eee eeeeeeeee eeee Me8M (8 ×), eee eee eeeeeeee eeeeeee eeeeee eeee eeeeee eeee eeeee, eeeee, eee eeeeeeeeeeee. Mee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, Me8M/eeeeeee 8:8); eeeee: 888 ee (88%); 88% ee; [α]M −88.8 (e 8.88, MeMM).
References
| [51] | Meeeee, M. M.; Me, M. M.; Meee, M., Meeeeeeee, (8888), 8888. |
| [52] | Meee, M. M.; Meeeeee, M. M.; Meeeeeee, M. M., Meeeeee, (8888), 88. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 88-8, 8888.
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