Haruki Tsuruta

An improved synthesis of (S)-aspartyl-(7,7-dimethylnorborn-2R-yl)-(S)-alanine methyl ester, a new high intensity artificial sweetener

Abstract (S)-Aspartyl-(7,7-dimenthylnorborn-2R-yl)-(S)-alanine methyl ester ( 1 ) was synthesized in nine steps from (+)-α-fenchyl alcohol ( 3 ) as a chiral synthon. Crucial steps for controlling the side-chain stereochemistry of 1 , required for the manifestation of sweetness, were the catalytic hydroformylation of the olefin 4 and the enzymatic resolution of the racemic amino acid 9 using acylase I.

The sweetness and stereochemistry of l-aspartyl-fenchylaminoalcohol derivatives

Abstract Four fenchylaminoalcohols were derived from ( + )-fenchone in five steps. They were resolved with ( + )- and (−)-tartaric acid, then condensed with N-carbobenzoxy-L-aspartic acid β-benzylester followed by hydrogenolysis to give four L-aspartyl-fenchylaminoalcohols. By the evalution of their taste, only (2R,3R)-aminoalcohol showed potent sweetness.

A Facile Synthesis of (2R 3S)-1-Amino-3-tert-butoxycarbonylamino-2-hydroxy-4-phenylbutane;A Useful Component Block of HIV Protease Inhibitor

Abstract (S)-3-tert-Butoxycarbonylamino-1-nitro-2-oxo-4-phenylbutan 4 was converted to (2R, 3S)-1-amino-3-tert-butoxycarbonylamino-2-hydroxy-4-phenylbutane 5a by a catalytic hydrogenation, or NaBH4-TiCl4 reduction followed by hydrogenation in favorable diastereoselectivity, a component of the HIV protease inhibitor VX-478.

A Convenient Synthesis of α-Fenchol from trans-2-Pinanol Using a Solid Acid Catalyst

ABSTRACT trans-2-Pinanol was directly rearranged to give α-fenchol in good yield by heating with aluminum phosphate as a solid acid catalyst.

Enantioselective Synthesis of (S)-3-(4-Thiazolyl)-2-tert-butoxycarbonylaminopropionic Acid: A Chiral Building Block for Renin Inhibitor

(S)-3-(4-Thiazolyl)-2-tert-butoxycarbonylaminopropionic acid (6), an important structural constituent of the renin inhibitor, has been synthesized from (Z)-3-(4-thiazolyl)-2-benzoylaminoprop-2-enoic acid (4b) by enantioselective hydrogenation using the Ru-(S)-p-tolyl-BINAP complex as the key step, and then followed by acid hydrolysis and tert-butoxycarbonylation.

Synthesis of nopinone from beta-pinene by oxidative system of RuCl3-NalO4-phase transfer catalyst[]

Abstract Nopinone was synthesized from β-pinene by an oxidative system of a RuCl3NalO4-phase transfer catalyst in 89% yield. Using this oxidative system, α-fencho-camphorone and camphenilone were also synthesized from α-fenchene and camphene, in 75% and 78% yield, respectively

The synthesis of (2R,3R)‐3‐(L‐Aspartylamino)‐1‐[(2S,3R)‐3‐methyl‐2‐norbornyl]‐2‐butanol, An excellent sweetener

Some L-aspartylnorbornylamino alcohol derivatives were synthesized as potential peptide sweeteners. Of these compounds, 3-(L-aspartylamino)-1-(3-methyl-2-norbornyl)-2-butanol displays an excellent sweetness potency. By further synthesis of one diastereoisomer, (2R,3R).3-(L-aspartylamino)-1-[(2S,3R)-3-methyl-2-norbomyl]-2-butanol, we obtained an excellent and potent sweetener.

The Synthesis and Stereochemistry of Methyl Substituted Bicyclo[2.2.1] heptane-2-carboxaldehydes

Abstract Three methyl substituted bicyclo[2.2.1]heptane-2-carboxaldehydes, thus, 1,3,3-trimethylhicyclo[2.2.1]heptane-2-carboxaldehyde, 1,7,7-trimethylbicydo[2.2.1]-hep-tane-2-carboxaldehyde, and 7,7-dimethylbicyclo[2.2.1]heptane-2-carboxaldehyde, were synthesized from the corresponding methylene compounds by epoxidation, followed by a rearrangement using boron trifluoride diethyl etherate. The endo/exo stereochemistry of these aldehydes was determined by NMR. The stability of these aldehydes was predicted by an MM2 model calculation and the calculated endo/exo isomer ratios are in fair agreement with the observed values.