Polyprenyl phenols

SnCl4 is also superior to 22 SnCl4, and is effective for the enantioselective cyclization of 2-(polyprenyl)phenol derivatives to give polycyclic terpenoids bearing a chroman skeleton.The synthetic utility of 26 SnCl4 is demonstrated by very... 

Chiral catechol-derived LBA (16) was devised as a new artificial cyclase for polyprenoids by the same group in 2004 (Scheme 1.24) [27]. The synthetic power of the new chiral LBA (16) has been well demonstrated by enantioselective cyclizations of various 2-(polyprenyl)phenol derivatives with good to excellent enantioselectivities (88-90% ee), leading to the efficient asymmetric syntheses of (-)-chromazonarol, (+)-8-epi-puupehedione, and (-)-ll -deoxytaondiol methyl ether. 

Phthalimide-N-sulfenyl chloride, 375 Phthaloylamino acids, 212 Phthaloyl-L-valine, 212 Phytuberin, 197 Phytyl chloride, 499, 500 Picrotoxinin, 265, 430 Pictei-Spengler cyclization, 308 Pinacol-typc reduction, 513 -Pinene, 346, 367 Piperidine acetate, 318 Piperidinium acetate, 375-376 Polonovski reaction, 484 Polyaminolactams, 378-379 Polycyclic phenols, 102 Polyene cyclization, 291-292 Polyethylene glycols, 360, 376 Polyketides, 302 Polyphosphate ester, 376-377 Polyprenylation, 499-500 Potassium-Ammonia, 273, 377 Potassium-t-Butylamine-18-Crown-6, 377-378... 

BF3 Et20 is used for the regioselective rearrangement of polyprenyl aryl ethers to yield polyprenyl substituted phenols, e.g. coenzyme Q [92]. This reagent is used in the Fries rearrangement for example, 5-acetyl-6-hydroxycoumaran is obtained in 96 % yield from 6-acetoxycoumaran by use of this reagent (Eq. 48) [93]. 

Approaches such as those described above which rely on the isolation and detection of polyprenyl substituted phenols and quinones in lipid extracts are restricted by the minute quantities of compounds present and the difficulties, frequently encountered, in establishing a precursor relationship between the suspected intermediate and ubiquinone. Gibson and his colleagues approached the problem of ubiquinone biosynthesis in Escherichia coli K-12 by the isolation and examination of mutants unable to form ubiquinone. Five classes of ubiquinone deficient mutants were... 

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