Bomane sultam

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. ... 

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

Nitroalkenes 278, prepared from aldehydes and nitromethane, have been shown (in unlabeled pilot studies designed for later carbon-13 experiments) to add to chiral titanium enolates of A -acylated (25)- or (27 )-bomane-10.2-sultams (279) in excellent diastereo-... 

The Al-acylation of lithiated (25)- or (2/f)-bomane-10,2-sultam 1921 (Figure 6.34) with bromo[ " C]acetyl bromide illustrates the ready accessibility of bromo[ C]acetyl (25)- or (2R)-bomane-10,2-sultam ((25) or (2R)-[ C]BABS, 93). Compound 93 is a versatile building block for the synthesis of e.p. carbon-14-labeled a- and /3-amino acids,... 

Figure 77.39 Diastereoselective a-alkylation of a N-([1 C ]acyl)bomane-10,2-sultam using an unlabeled functionalized alkylating agent...

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