+++синтез изоксазола спасибо всем!

[AlexDon]

Уважаемые коллеги, посмотрите, пожалуйста, синтез изоксазол 3,5-диметил-4карбальдегида

Cc1c(c(on1)C)C=O

Спасибо за помощь!

[Serty]

Reaxys
Надо же, а мне казалось, что его можно получить проще - формилированием

[Arkadii_Tarasevych]

СкайФайндер

1. Facile synthesis of isoxazole-4- and -5-carboxaldehydes and their conversion to isoxazolyl-1,4-dihydropyridines By Mirzaei, Y. R.; Bavili-Tabrizi, S.; Hashemi-Gohare, M.; Zare-Neirizi, H.; Edjlali, L. From Organic Preparations and Procedures International (2003), 35(2), 207-214. Language: English, Database: CAPLUS
Isoxazolecarboxaldehydes were prepd. by oxidn. of isoxazolemethanols with BaMnO4. Cyclocondensation of the aldehydes with Et acetoacetate and NH3 gave isoxazolyl-1,4-dihydropyridines such as I and II.
SubstancesReactions~3 Citings

2. Modification of sidechains at C-4 position of isoxazole rings by Wittig and Grignard reactions By Alberola, A.; Perez Serrano, A.; Rodriguez Rodriguez, Maria T.; Orozco, C. From Anales de Quimica, Serie C: Quimica Organica y Bioquimica (1989), 85(1), 13-17. Language: Spanish, Database: CAPLUS
Isoxazolylmethylphosphonium salt I (R = Ph3P+CH2 Cl-, R1 = Me) underwent Wittig reactions with aldehydes R2CHO (R2 = alkyl, aryl) to give C-4 elongated derivs. I (R = R2CH:CH). Aldehydes I (R = CHO, R1 = Me, Ph) were prepd. and underwent similar Wittig reactions with P ylides as well as Grignard reactions to give carbinols I (R = HOCHR2, where R2 = alkyl, aryl).
SubstancesReactions~0 Citings

3. Synthesis of 4-carbo substituted isoxazole derivatives By Alberola, Angel; Perez Serrano, Antonio; Rodriguez Rodriguez, Maria Teresa; Orozco, Carmen From Heterocycles (1989), 29(4), 667-77. Language: English, Database: CAPLUS
3,5-Disubstituted 4-lithioisoxazoles I (R = Li; R1 = R2 = Me, Ph; R1 = Me, R2 = Ph) (II) were synthesized selectively and in good yields by lithium-halogen exchange between 4-bromoisoxazoles I (R = Br) and BuLi. Reaction of II with satd. or α,β-unsatd. carbonyl compds., esters, nitriles, and amides allow the introduction of carbon chains with different functionality at C-4, e.g. I (R = HOCR3R4, R1, R2 = same; R3 = Me, Et, Ph, PhCH:CH, Me2C:CH, R4 = H, Me).
SubstancesReactions~2 Citings

4. The mass spectral fragmentation of isoxazolyldihydropyridines By Knerr, Gary; McKenna, John I.; Quincy, David A.; Natale, N. R. From Journal of Heterocyclic Chemistry (1987), 24(5), 1429-33. Language: English, Database: CAPLUS
The mass spectral fragmentation of 4-isoxazolyl-1,4-dihydropyridines I (R = H, D; R1 = Me, Et; R2 = Me, Et, Ph; R3 = Et, Me) has been examd. with the aid of linked metastable scanning. Three prominent paths involve (i) O-N bond cleavage of the isoxazole followed by the loss of R2CN, (ii) loss of carbalkoxy from the 3- and/or 5-position of the dihydropyridine and, (iii) loss of the 4-isoxazolyl-substituent.
SubstancesReactions~1 Citing

5. Neutral dichromate oxidation. Preparation and utility of isoxazole aldehydes By Natale, Nicholas R.; Quincy, David A. From Synthetic Communications (1983), 13(10), 817-22. Language: English, Database: CAPLUS
Isoxazolemethanols I (R = Me, Et; R1 = Me, Ph) were converted to dihydropyridines II, useful as Ca channel blockers (no data), via aldehydes III. I (R = R1 = Me) was heated with K2Cr2O7 in EtOAc contg. Adogen 464 under Ar to yield III (R = R1 = Me), and a mixt. of the latter, MeCOCH2CO2Et, and aq. NH3 in EtOH was refluxed overnight to give II (R = R1 = Me).

[Arkadii_Tarasevych]

Да, всё же можно и формилированием. Сначала литируют бромоксазол, а затем прибавляют ДМФА.