Synthesis of the lower subunit of rhizoxin

Boger, Dale L.; Curran, Timothy T.

doi:10.1021/jo00034a010

Cited by 50 publications

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“…The 4-methyloxazole-2-carbaldehyde [22] (5) was synthesized by nBuLi/DMF formylation from the corresponding oxazole 9. Compound 2-methyl-oxazole-4-carbaldehyde [25] (7) was prepared from the commercially available ester 12 by diisobutylaluminum hydride (DIBAL-H) mediated reduction by following the described procedure for the oxazole-4-carbaldehyde. This reaction gave a mixture of oxazole-2-and oxazole-5-carbaldehyde, [22] in which the 5-carbaldehyde 6 was the major product, but was impossible to purify due to its extreme volatility.…”

Section: Resultsmentioning

confidence: 99%

“…The approach was changed and compound 6 was synthesized by a two-step reaction pathway from the corresponding ester 10, [23] via alcohol 11, [24] in a good overall yield of 60 % (Scheme 2). Compound 2-methyl-oxazole-4-carbaldehyde [25] (7) was prepared from the commercially available ester 12 by diisobutylaluminum hydride (DIBAL-H) mediated reduction by following the described procedure for the oxazole-4-carbaldehyde. [26] 2-Phenyl-oxazole-4-carbaldehyde [27] (8) was prepared from 5bromo-2-phenyloxazole [27] (14) in two steps.…”

Section: Resultsmentioning

confidence: 99%

“…Isomers were separated by repeated column chromatography on silica gel using PE/E (variable ratio) to give cis-4-methyl-5- [25] This compound was synthesized according to the literature for oxazole-4-carbaldehyde [26] from methyl-2-methyloxazole-4-carboxylate (12). The reaction mixture was stirred for 1 h. Under a stream of dry nitrogen, gaseous formaldehyde (obtained by decomposition of paraformaldehyde taken in excess, 1.5 g) was introduced together with a second quantity of sodium.…”

Section: -Methyl-5-[2-(2-vinylphenyl)ethenyl]oxazole (2)mentioning

confidence: 99%

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Versatile Photochemical Reactivity of Diverse Substituted 2‐, 4‐ and 5‐(o‐Vinylstyryl)oxazoles

et al. 2018

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To study the effects of the position of the hexatrienyl moiety on the oxazole ring, novel substituted cis/trans‐2/4/5‐(2‐vinylstyryl)oxazoles have been synthesized. These novel compounds were prepared by Wittig reaction from the diphosphonium salt of α,α′‐o‐xylenedibromide, formaldehyde and the corresponding 2‐methyl‐4‐, 4‐methyl‐2‐, 2‐pheny‐5‐ and 4‐methyl‐5‐oxazolecarbaldehyde, respectively. Aldehydes were synthesized by using several synthetic approaches. By applying intramolecular photocycloaddition, 2‐methyl‐4‐(2‐vinylstyryl)oxazole afforded, as major product, fused oxazoline‐benzobicyclo[3.2.1]octene with small quantities of 4‐(1,2‐dihydronaphthalen‐2‐yl)‐2‐methyloxazole, as electrocyclization product. Upon irradiation of 4‐methyl‐5‐(2‐vinylstyryl)oxazole, endo‐ and exo‐benzobicyclo[2.1.1]hexene products were formed by [2+2] cycloaddition; this was the first instance of the 1,4‐closure to the bicyclo[2.1.1]hexene skeleton in the 2‐, 4‐, and 5‐oxazole‐stilbene derivatives studied so far. Derivatives 2‐phenyl‐5‐ and 4‐methyl‐2‐(2‐vinylstyryl)oxazole did not react and gave only high‐weight molecular products but were crucial as a comparison in the overall mechanistic study. We have found that, depending on the position of the hexatrienyl moiety in the oxazole ring, as well as on the position of the methyl/phenyl substituents, these new vinylstyryl‐2/4/5‐oxazole derivatives show diverse photochemical behavior.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: -Methyl-5-[2-(2-vinylphenyl)ethenyl]oxazole (2)mentioning

confidence: 99%

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Versatile Photochemical Reactivity of Diverse Substituted 2‐, 4‐ and 5‐(o‐Vinylstyryl)oxazoles

et al. 2018

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“…[21] Selected phosphonium salts (2-4) were combined with oxazole-4-carbaldehyde (1a) [22] or 2-methyl-oxazole-4carbaldehyde (1b), [23] using sodium ethoxide as base (Scheme 1). [21] Selected phosphonium salts (2-4) were combined with oxazole-4-carbaldehyde (1a) [22] or 2-methyl-oxazole-4carbaldehyde (1b), [23] using sodium ethoxide as base (Scheme 1).…”

Section: Full Papermentioning

confidence: 99%

“…[21] Selected phosphonium salts (2-4) were combined with oxazole-4-carbaldehyde (1a) [22] or 2-methyl-oxazole-4carbaldehyde (1b), [23] using sodium ethoxide as base (Scheme 1). The required p-and ophenyl-substituted 5-arylethenyloxazoles were prepared from the corresponding α, -unsaturated aldehydes and the TosMIC reagent (tosylmethyl isocyanide) by the Van Leusen reaction.…”

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Synthesis of Naphthoxazoles by Photocyclization of 4‐/5‐(Phenylethenyl)oxazoles

et al. 2018

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Promising test results on the biological activity of our previously described naphtho[1,2‐d]oxazoles and heterobenz[1,2‐d]oxazoles, obtained by the photochemical cyclization of 5‐phenylethenyl‐ and 5‐heteroarylethenyloxazoles, prompted us to continue with the photochemical synthesis of substituted naphtho[1,2‐d]oxazoles, and to extend the photochemical cyclization to the synthesis of naphtho/heterobenz[2,1‐d]oxazoles from 4‐(aryl/heteroarylethenyl)oxazoles. The required p‐ and o‐phenyl‐substituted 5‐arylethenyloxazoles were prepared from the corresponding α,β‐unsaturated aldehydes and the TosMIC reagent (tosylmethyl isocyanide) by the Van Leusen reaction. The substituted 4‐(aryl/heteroarylethenyl)oxazoles were prepared by the Wittig reaction starting from various phosphonium salts and 2‐H/methyl‐4‐oxazolecarbaldehydes.

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Lithium Tri-s-butylborohydride

Hubbard¹

2001

Encyclopedia of Reagents for Organic Synthesis

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Synthesis of the lower subunit of rhizoxin

Cited by 50 publications

References 0 publications

Versatile Photochemical Reactivity of Diverse Substituted 2‐, 4‐ and 5‐(o‐Vinylstyryl)oxazoles

Versatile Photochemical Reactivity of Diverse Substituted 2‐, 4‐ and 5‐(o‐Vinylstyryl)oxazoles

Synthesis of Naphthoxazoles by Photocyclization of 4‐/5‐(Phenylethenyl)oxazoles

Lithium Tri-s-butylborohydride

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