A Case of Abnormal Bishler-Napieralski Cyclization Reaction,Leading to Form Benzyl Oxazole Derivatives

1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is a type of naturally occurring bio-active alkaloid1. Moreover, it can be used as building block for the synthesis of other natural products containing the 1,2,3,4-tetrahydroisoquinoline moiety2. Compound 2 was an intermediate in our attempt to the total synthesis of Ecteinascidin analogs. We employed the Bishler-Napieralski reaction to prepare this product and refluxed the N-acetyl phenylalanine compound 1 in POCl3/benzene. However, we fail…     

A New Sesquiterpene Lactones Glucoside from Notoseris psilolepis

As a part of an investigation on plant of the genus Notoseris (Asteraceae), an endemic genus of seed plants of China1, we studied the chemical constituents of N. psololepis Shih. A new sesquiterpene lactone glucoside, named notoserolide C (1) was isolated from the methanolic extract of the whole plant of N. psilolepis by repeated column chromatography (MCI GEL, normal and reversed phase silica gel). This compound showed antibacterial activity against Bacillu cereus.Figure 1. The key HMB…     

A New Indole Alkaloid from Limonia Crenulata

Limonia crenulata Roxb. (Rutaceae), a small tree widely distributed in dry warm regions of southeastern Asia, has been reported to have antiepileptic, purgative and sudorific effects and is used for colic trouble and cardialgia1. Various parts of this plant have been employed in indigenous medicine. Our investigation on its stems led to the isolation of one new alkaloid, crenulatine 1, together with three known ones, 4-methoxy-6- hydroxy-1-methyl-2-quinolone2, N-benzoyltyramine methyl ether2,…     

A Novel Synthesis of Dimethyl Malonate by Carbonylation of Methyl Chloroacetate Catalyzed by Cobalt Complex

Dimethyl malonate (DMM) is an important organic synthesis intermediate. Traditional synthetic method by reaction of mono-chloroacetic acid with sodium cyanide1 is poisonous and complicated. Therefore, an interest in green synthesis routes of DMM has risen greatly. The several processes for preparing DMM by carbonylation of methyl chloroacetate catalyzed by Co2(CO)8 have been reported2~5. However, Co2(CO)8 is unstable and must be prepared under high pressure (12 Mpa). Moreover, the yield…     

The Synthesis of 19-Nor-1α, 25-dihydroxy-22-oxo-vitamin D_3

Since the last decade, there has been a growing interest in the development of analogues of 1(, 25- dihydroxyvitamin D3 1 with low calcemic effect but increased cell differentiating ability1. Among side chain and the A-ring modifications of 1, the 1(, 25- dihydroxy-22-oxo-vitamin D3 22 and 19-nor-1(, 25- dihydroxyvitamin D3 33 have shown much lower calcemic effect and stronger cell differentiating ability than 1. In this paper, we reported synthesis of 19-nor-1(, 25-dihydroxy-22-oxo-vitamin …     

Total Synthesis of (±)-Nimbonone and (±)-12-Ethyl-13-methoxy- 8,11,13-podocarpatriene

Most diterpenoids exhibit significant bioactivities, such as antidermatophytic, antibact- erial, and antioxidant. Although a large number of aromatic tricyclic diterpenoids have been isolated, there are a few of them having ethyl substituent. The synthesis of this type diterpenoids has been seldom reported. In order to further study the relationship between the structure and bioactivities of the diterpenoid, we extended the diterpene synthesis1,2,3. It is desirable to report herein the syn…     

The First Total Synthesis of Isoliquiritin

Isoliquiritin 1 was isolated from the roots of G. uralensis and also from other plants, and has been reported to exhibit antitumour, anti-HIV, curing hepatitis activities1, 2, use as anti-allergic drug4, and for sweetening3. It has been used for a strong inhibitor of hyaluronidase4. HOOHOOGluc561'2'3'4'5'6'1243βα1 OHHOOHHHHOHHOHGluc=2"3"4"6"1"5" The synthesis of isoliquiritin (4-glucopyranoxy-2,4-dihydroxy chalcone) has not been reported, because there is no suitable synth…