Asymmetric dihydroxylation of geranyl, neryl and trans, trans-farnesyl acetates

Vidari, Giovanni; Dapiaggi, A.; Zanoni, Giuseppe; Garlaschelli, Luigi

doi:10.1016/0040-4039(93)85077-a

Cited by 71 publications

(39 citation statements)

References 14 publications

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“…Vidari et al [22] have described an efficient, highly enantioselective dihydroxylation of geranyl acetate (92% yield, 98% ee) employing the AD-mix system developed by Sharpless and co-workers. [23] In our case, however, treatment of 5 with AD-mix-a gave only a 10% yield of diol (À)-9 (Scheme 3), which still had to be transformed into epoxide 3.…”

Section: Resultsmentioning

confidence: 98%

Titanium‐Catalyzed Enantioselective Synthesis of α‐Ambrinol

et al. 2008

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We describe the first enantioselective synthesis of the odorant compound (À)-a-ambrinol (96% ee) from commercial geranylacetone. The key steps are a Jacobsens asymmetric epoxidation and a titanium-catalyzed stereoselective cyclization initiated by radical epoxide opening. The oxirane ring opening proceeds with retention of configuration at the epoxide chiral center, giving a secondary alcohol which can be advantageously exploited to raise the ee provided by the synthetic sequence. We also synthesized (+)-a-ambrinol by a closely related procedure, showing the synthetic versatility of combining titanium-catalyzed cyclization with Jacobsens epoxidation reactions.

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Section: Resultsmentioning

confidence: 98%

Titanium‐Catalyzed Enantioselective Synthesis of α‐Ambrinol

et al. 2008

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“…13h Alternatively, catalytic asymmetric dihydroxylation of geranyl acetate in the presence of AD-mix-β at 0°C for 24 h gave (-)-6(S),7dihydroxy-geraneol, whereas AD-mix-α gave (+)-6(R),7-diol. [18,19] Similar treatment of farnesyl acetate through terminal double bond dihydroxylation, mesylation and base catalysed elimination yielded 10(S),11-epoxy-farnesyl acetate ( Table 1, entry 17). [18,19] Similar treatment of farnesyl acetate through terminal double bond dihydroxylation, mesylation and base catalysed elimination yielded 10(S),11-epoxy-farnesyl acetate ( Table 1, entry 17).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of the fragrance terpene epoxides and selective monocyclization promoted by camphor and oxone®

Gaikwad

Kabiraj

Bhat

2016

Flavour & Fragrance J

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A high level of regio‐selectivity in the epoxidation of monoterpenes with camphor and oxone® at pH 7 has been observed. This methodology when applied to acyclic terpenes such as citronellyl acetate, geranyl acetate yielded mainly chiral 6(S),7‐epoxides. Similarly, farnesyl acetate yielded 10(S),11‐epoxide. Alternatively, unsaturated monocyclic terpene alcohol such as (‐)‐α‐terpineol, 6‐methyl‐hept‐5‐en‐2‐ol, when treated with camphor and oxone® at pH ~4‐5 led to one‐pot oxidative‐cyclization to yield (‐)‐trans‐2‐(S)‐hydroxy‐1,8‐cineole and (+)‐2,2,6‐trimethyl‐tetrahydropyran‐3‐ol respectively. In addition, the epoxides, trans‐2‐hydroxyl‐cineole and its acetate synthesized herein have good perfumery value with woody and sweet aromas. Copyright © 2016 John Wiley & Sons, Ltd.

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“…To this purpose we prepared (10S)-10,11-epoxy-farnesyl acetate (8) starting from (2E,6E)-farnesyl acetate (6) using a procedure described by Vidari et al 12 Highly enantioselective dihydroxylation of (2E,6E)-farnesyl acetate (6) employing AD-mix-b afforded diol 7. Conversion of diol 7 to the corresponding 10-O-mesylate followed by reaction with K 2 CO 3 in CH 3 OH gave (10S)-10,11-oxidofarnesol, which was subjected to acetylation affording 8.…”

Section: Resultsmentioning

confidence: 99%

“…The combined organic phases were dried (anhydrous Na 2 SO 4 ), filtered, and evaporated in vacuo. The crude product was flash chromatographed (from 15% AcOEt in petroleum ether to pure AcOEt) to afford 32 mg (58%) of 13 as white matt solid,12.6 mg (23%) of D 8,9 double bond isomer 14 as a white solid. Compound 13: [Found: C, 68.67; H, 11.35.…”

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confidence: 99%