Alanine furyl

In this section we refer to types of addition to the carbonyl group, which by their very nature lead to C4-elongation. Examples are found in the addition of furan derivatives and [4+2] cycloaddition. We have recently described [39] the stereoselective addition of 2-furyl-lithium 26 to N,N-diprotected alaninals. For example, the reaction of 26 with alaninal 25 led to a mixture of diastereoisomers syn-21 and anti-28, with predominance of the latter isomer (Scheme 10). A similar method was used in the synthesis of methyl a-D-lincosaminide (see Sec. III.F). 

The sequence with oxazole 73 also proves to be applicable to systems in which the double bond of the allylic alcohol fragment is incorporated into a heteroaromatic ring, such as in furfuryl alcohol (77a) and thiophene-2-methanol (77b).28 After hydrolysis of the oxazolone ring with water, V-benzoyl-3,3,3-trifluoro-2-(2-methyl-3-furyl)alanine (79a) and /V-benzoyl-3,3,3-trifluoro-2-(2-melhyl-3-thienyl)alanine (79b) are obtained. The 2-methylene helerocyclcs 78 originally formed in the Claisen rearrangement undergo rearomatizalion under the reaction conditions. 

Fmoc-amino acids used as building blocks of testing compounds are as follows Fmoc-Asp(OtBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Asn(Trt)-OH, Fmoc-Gln(Trt)-OH, Fmoc-Met-OH, Fmoc-Glu(OtBu)-OH, Fmoc-Lys (Boc)-OH, Fmoc-Ile-OH, Fmoc-His(Trt)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-Arg(Pmc)-OH, Fmoc-Phe-OH, Fmoc-Ser(tBu)-OH, Fmoc-Thr(tBu)-OH, Fmoc-Val-OH, Fmoc-Pro-OH, Fmoc-Trp(Boc)-OH, Fmoc-D-Ala-OH, Fmoc-D-Arg(Pmc)-OH, Fmoc-D-Trp(Boc)-OH, Fmoc-D-Cys(Trt)-OH, Fmoc-D-Asp(OtBu)-OH, Fmoc-D-Glu(OtBu)-OH, Fmoc-D-His(Trt)-OH, Fmoc-D-Gln(Trt)-OH, Fmoc-D-Leu-OH, Fmoc-D-Met-OH, Fmoc-D-Pro-OH, Fmoc-D-Ser(tBu)-OH, Fmoc-D-Lys(Boc)-OH, Fmoc-D-Tyr(tBu)-OH, Fmoc-D-Thr(tBu)-OH, Fmoc-D-Phe-OH, Fmoc-D-Asn(Trt)-OH, Fmoc-3-(4-pyridyl)alanine, Fmoc-D-3-(3-pyridyl)alanine, Fmoc-4-tert-butoxyproline, Fmoc-3-chlorophenylalanine, Fmoc-norleucine, Fmoc-2-cyclohexylglycine, Fmoc-2-aminoisobutyric acid, Fmoc-tranexamic acid, Fmoc-(i ,S)-3-amino-3-(2-furyl)propionic acid, Fmoc-(i ,S)-(6,7-di-methoxy)-l,2,3,4-tetrahydroquinoline-3-carboxylic acid, Fmoc- (R, S)-3-amino-3-(4-hydroxyphenyl)propionic acid, Fmoc-(i ,S)-3-aminovaleric acid, Fmoc-(i ,5 )-3-amino-3-(3,4-dichlorophenyl)propionic acid, Fmoc-isonipecotic acid, Fmoc-(i ,S)-3-amino-3-(3,4-methylenedioxyphenyl)... 

Bitter compounds are also formed in solutions of alanine with xylose and rham-nose.284 Twenty-six HPLC fractions were obtained, seven of which were shown to have high impact on taste dilution analysis. Structures 37-41 accounted for 57% of overall bitterness. The compounds have low threshold values introduction of methyl groups into the furyl rings increase the threshold value. On the contrary, substituting the furyl ring-0 by S (42) lowered the threshold value to almost 104 times lower than that of caffeine on a molar basis. 

Hill and Edwards (34) have determined the absolute configuration of the C-2 position as S by alkaline permanganate oxidation of (—)-A-benzoyl-3-furyl-P-alanine (14) to L-(+)-A-benzoylaspartic acid, using the conditions developed by Reichstein et al. (55) for the oxidation of the furan ring. Compound 14 is the starting material for the synthesis of the (-I-) enantiomer of febrifugine according to Baker et al. 

Tyrosine, aminophenyl-alanine, dimethylamino-phenylalanine, tryptophan, and -furyl(2)-alanine consumed > 1 atom 0... 

Dimetbylamino-phenylalanine consumed > 1 atom O, f-AT-Sul-fanilyllysine not attacked -Quinolyl(2)al-anine > /9-quin-olyl(4)alanine Tyrosine, amino-phenylalanine, dimethylami nophenylalanine, tryptophan, and 0-furyl (2)alanine consumed > 1 atom 0 Histidine and c-AT-sulfanilyllysine not attacked Tyrosine, aminophenyl-alanine, dimethylamino-phenylalanine, <-Af-sulfanilyllysine consumed > 1 atom 0 p-0 -Aminoethy 1)-phenylalanine, p-aminophenylala-nine, p-(Umethyla-minophenylalanine, pyridyl (4)alanine, tyrosine consumed > 1 atom of 0 ... 

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