Bomane sultams

The camphorylsulfinylimine (146) with lithium aliuninum hydride is reduced to the (2/ )-10,2-bomane sultam (147) (R = Y = H), and reaction with methyl magnesium iodide in the presence of copper(I) chloride gives the methyl analog (147) (R = Me, Y = H) <88TL6087>. The fluorination of... 

An interesting asymmetric aldol reaction utilizing enantiomerically homogeneous bomane sultam derived boron enolates has recently been reported by Oppolzer et al. The reaction of aldehydes with boron enolates (57), generated from acyl sultams (58) under standard enolization conditions (Pr 2NEt/Bu2BOTf/0 C), provides syn aldol products (59) with extremely high ratios of (59) to (60) as shown in Scheme 29. Results from the aldol reactions with representative aldehydes are summarized in... 

Substituted 3-hydroxy-2-pyrrolidinones were synthesised via 1,3-DC reactions of furfuryl nitrones with acrylates and subsequent intramolecular cyclisation after N-0 bond reduction. Addition of iV-acryloyl-(2/()-bomane-10,2-sultam to Z-nitrone 83 gave the endo/exo cycloadducts in 85 15 ratio with complete stereoface discrimination <00JOC1590>. The 1,3-DC of pyrroline A-oxide to chiral pentenoates using (-)-/rans-2-phenylcyclohexanol and (-)-8-phenylmenthol as chiral auxiliaries occurred with moderate stereocontrol (39% de and 57% de, respectively) and opposite sense of diastereoselectivity <00EJO3595>. The... 

A rather rare case is the use of chiral nitrile oxide, derived from N-glyoxyloyl-(2i )-bomane-10,2-sultam (211). Several nitrile oxides of the latter type, bearing... 

Stereochemical control of intramolecular 1,3-dipolar cycloadditions by route b (Scheme 2.211) was realized in the asymmetric synthesis of l-azaspiro[4.5] decanes by using the chiral (2R)-bomane-10,2-sultam (X ) auxiliary in the dipo-larophilic fragment (Scheme 2.220) (718). 

Nitrosocarbonyl-D-bomane-10,2-sultam 233 adds to cyclopentadiene to yield 234 with complete facial selectivity (equation 123)114. 

The use of chiral A-acylated sultams 1 as auxiliaries for diastereoselective alkylation and related reactions has emerged as a useful and versatile method for the construction of chiral compounds. Both enantiomers of 10.10-dimethyl-4-a2a-3-thiatricyclo[S.2.1,0 -5]decane 3,3-dioxide (bomane-10,2-sultam) have been employed1-6 and are now commercially available. A chiral sultam prepared from saccharin has also been used for a variety of asymmetric transformations8,9. 

Obtained by ozonolysis of N-crotonoyl- or /4-fumaroyl-(2/7)-bomane-10,2-sultam [50]. Prepa ration of (2/f)-bomane-10,2-sultam W. Oppolzer, C. Chapuis, and G. Bemardinelli, Helv. Chim Acta 67 1397 (1984). 

Bomane-10,2-sultam (362) and its antipode, accessible from inexpensive (+)- and (-)-camphorsulfonic acid in two simple operations, were introduced in 1984 and rank today among the most practical auxiliaries (Scheme 88). Both chirophore enantiomers are commercially available in kg quantities. Almost all of their A -acyl derivatives are stable and can be (1) readily purified by crystallization, (2) directly analyzed by H NMR and/or GC to determine their stereochemical purity, and (3) cleaved e.g. with UAIH4, LiOH, LiOOH, MeOMgl, etc.) under mild conditions without loss of the induced chirality and with excellent recovery of the auxiliary. 

An asymmetric synthesis of a-amino acids starts from free radical addition to W-(benzyloxyiimnoacetyl)-bomane-10,2-sultam. The adducts are then treated with Mo(CO) and LiOH sequentially. 

W-(p-toluenesulfinyl)bomane-10,2-sultam in the (/Jj-form delivers the sulfinyl group to various nucleophiles. Thus, chiral vinyl sulfoxide and p-toluenesulfinimines are readily prepared. Enantiopure ketones can be obtained from l,2-bis(benzenesulfonyl)alkenes via acetal formation with chiral diols such as (+)-l,2-diphenylethane-l,2-diol. ... 

Pauson-Khand reaction. The intermolecular Pauson-Khand reaction of N- 2-alkenoyl)bomane-IO,2-sultams is totally stereoselective. The catalytic P-K reaction is promoted by small quantities of DME (or other hard bases including water). Reactions carried out in supercritical carbon dioxide are very efficient regardless of the substitution pattern of the alkyne unit. ... 

Oppolzer and coworkers [147, 454] have developed a class of reagents based on the enantiomeric bomane-2,10-sultam skeleton 1.133. These chiral auxiliaries are easily prepared from the enantiomeric 10-camphosulfonic adds [455]. Saturated or a,P-unsaturated TV-acylsultams 1.134, occasionally prepared from Af-silyl precursors [396], have been used very frequently. Asymmetric alkylations, animations and aldol reactions of enolates or enoxysilane derivatives of 1.134 (R = R CH2) [147, 404, 407, 456-460] are highly selective. The a,(3-unsaturated TV-acylsultams 1.134 (R = R R"C=CH) suffer highly stereoselective organocuprate 1,4-additions [147, 173], cyclopropanations [461], [4+2] and [3+2] cydoadditions [73,276,454,462], OSO4 promoted dihydroxylations [454,463] and radical addi-... 

Fig. 5. Asymmetric bromination of boxyl enolates of bomane-10,2-sultams...

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