S y n t h e s i s o f N -P r o t e c t e d 1 -S u b s t i t u t e d a n d 1 , 2 -D i s u b s t i t u t e d T a u r i n e sAbstract: N-Benzyloxycarbonyl protected a-substituted and a,bdisubstituted taurines were synthesized from olefins and epoxides via N-benzyloxycarbonylamino alcohol thioacetates as key intermediates. They are important sulfur analogues of naturally occurring amino acids and building blocks for the synthesis of asubstituted and a,b-disubstituted b-sulfonopeptides.There is a growing interest in the structural modification of natural peptides to overcome the limitations associated with their development as therapeutically useful agents, and to gain information on the nature and mechanism of the peptide-receptor interactions. 1-3 The phosphonamidate, phosphonate and sulfonamide-linked peptides are very important modified peptides and are recognized to be able to mimic transition-state analogues of hydrolysis of ester and amide bonds because of their tetrahedrally structural properties. During the last decade aminoalkylphosphonic acid and aminoalkanesulfonic acid derivatives, and phosphonopeptides and sulfonopeptides have been used as enzyme inhibitors and haptens in the development of catalytic antibodies. 4-7 Sulfonopeptides are more stable under both mildly acidic and basic conditions compared to phosphonopeptides and will be used more widely. b-Aminoalkanesulfonic acids are very important sulfur analogues of naturally occurring amino acids for the synthesis of sulfonopeptides because a-aminoalkanesulfonic acids and their derivatives are unstable. 8 There are three types of structural analogues of naturally occurring amino acids for b-aminoalkanesulfonic acids, which include 1-substituted taurines, 2-substituted taurines, and 1,2-disubstituted taurines (Figure 1). 2-Substituted taurines have been synthesized effectively from b-amino primary alcohols, 9-18 which were easily obtained by reduction of natural amino acids, from b-amino secondary alcohols 19,20 via sulfite displacement of their methanesulfonates, 9-12 peroxy acid oxidation of their thioacetates, 13-17,21 and sulfite ringopening of aziridines. 18 But little attention has been paid to the synthesis of 1-substituted and 1,2-disubstituted taurines 15,21,22 and their sulfonopeptides. 21,23,24 To synthesize structurally diverse sulfonopeptides, it is very important to develop an effective and general method for the preparation of 1-substituted and 1,2-disubstituted taurines. Herein we describe a general route to 1-substituted and 1,2-disubstituted taurines from olefins and epoxides. Figure 1 Taurine and substituted taurinesAs part of a program to synthesize structurally diverse sulfur analogues of naturally occurring amino acids, we sought to prepare 1-substituted and 1,2-disubstituted taurines. 1,2-Amino secondary alcohols are important key intermediates for synthesizing 1-substituted taurines. They could be prepared from available terminal olefins or 1,2-epoxyalkanes. Although alkenes could be converted to 1,2-N-protected amino alcohols di...

Model updating concerns the modification of an existing but inaccurate model with measured data. For models characterized by quadratic pencils, the measured data usually involve incomplete knowledge of natural frequencies, mode shapes, or other spectral information. In conducting the updating, it is often desirable to match only the part of observed data without tampering with the other part of unmeasured or unknown eigenstructure inherent in the original model. Such an updating, if possible, is said to have no spillover. Model updating with no spillover has been a very challenging task in applications. This paper provides a complete theory on when such an updating with no spillover is possible.

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