Oppolzer’s chiral sultam

On the contrary, application of Oppolzer s chiral sultam 100 in Method 1 led to good diastereoselectivity (d.e. 60-70% after chromatography), and pure (4R)-diastereomers have been isolated by recrystallization. Moreover, the chiral auxiliary was cleaved successfully by reduction with LiAlH4.2-Aminopyran-5-carbinols 101 were produced without... 

Further examples of the endocychc nitrone route to spirocychc adducts are the total syntheses of (—)-histrionicotoxin (230) by Holmes and of cyhndricines by Weinreb. Histrionicotoxin is one of many spiropiperidine alkaloids isolated from the poison-arrow frog Dendrobates histrionicus and has been the subject of many attempted total syntheses by a nitrone cycloaddition strategy that failed to provide the desired regioisomer, possibly through unfavorable steric interactions (265-268). Unlike these reports, Holmes and co-workers (101) found that the intermolecular reaction of nitrone (231), prepared by the 1,3-APT of the corresponding alkynyl-hydroxylamine carrying Oppolzer s chiral sultam auxiliary, afforded the styrene... 

One of the most successful auxiliaries for ot,p-unsaturated carbonyl compounds for not only 1,3-dipolar but also other cycloadditions is Oppolzer s chiral sultam (276). In particular, the acrylate 165 of Oppolzer s chiral sultam is one of the most frequently used substrates for asymmetric 1,3-dipolar cycloadditions, as shown in Scheme 12.52. 

For most of reactions of different 1,3-dipoles with Oppolzer s chiral sultam shown in Scheme 12.52, it has been demonstrated that the auxiliary can be recovered. 

Reactions of the Oppolzer s chiral sultam derivative (100a) with nitrile oxides showed considerable diastereoselectivity [88TL3555 90JOC4585 ... 

Diels-Alder reactions with Oppolzer s chiral sultam Diels-Alder reactions with pantolactone as chiral auxiliary Chiral auxiliaries attached to the diene Improved Oxazolidinones SuperQuats Asymmetric Michael (Conjugate) Additions... 

Diels-Alder reactions with Oppolzer s chiral sultam... 

Oppolzer s chiral sultam 120 is easily converted to the amide 144 with a, 3-unsaturated acid chlorides and reacts with dienes with the Lewis acid EtAlCl2 as catalyst. The adduct 145 is essentially a single compound and LiOH hydrolysis gives the simplest of all Diels-Alder adducts 146 as a single enantiomer in good yield.18... 

Miscellaneous. lodomethoxylation of chiral o ,/8-unsaturated amides has been described to afford a highly regioselective addition of NIS and methanol across an alkene in moderate diastereos-electivity using both Oppolzer s chiral sultam (eq 35) and Evans chiral oxazoUdinone. Subsequent cleavage of the chiral auxiliary, conversion of the iodide to the azide, and reduction to the amine results in synthetically useful a -amino acids. 

Acylation Catalyst. iV-Trimethylsilyl derivatives of (-1-)-bornane-2,10-sultam (Oppolzer s chiral sultam) and chiral 2-oxazolidinones (the Evans chiral auxiliaries) are Al-acylated with a number of acyl chlorides including acryloyl chloride in refluxing benzene in the presence of CuCl2 The M-acylated products were... 

The phosphodiesterase (PDE) IV inhibitor (109, Scheme 2.17) has been identified by Merck Research Laboratories as a potential lead for the treatment of asthma. Although an early synthesis of 109 relied on the use of Oppolzer s chiral sultam auxiliary, a more economic approach was subsequently developed that exploited an aminoindanol auxiliary. In the revised synthesis, the car-boxyhc acid 103 (available in two steps from isovanillin) is coupled with (15,2/ )-cis -aminoindanol 12 and subsequently converted into the amide 104. After protection of the amino alcohol, reaction of the resulting Michael acceptor 106 with phenyllithium 107 and subsequent... 

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