A Convenient Synthesis of 3-Methylthiobenzaldehyde

Requiring the title compound as a starting material, we were surprised to find only one published synthesis,¹ involving five steps with an overall yield of 15%. This is in contrast to the 2-and 4-alkylthiobenzaldehydes, which may be synthesised in one step by reaction of sodium alkanethiolates with the readily available halobenzaldehydes². 3-Halobenzaldehydes, although readily available, do not react under these conditions².     

A Convenient Synthesis of 3-Alkoxythiophene

3-Alkoxythiophenes could be conveniently prepared by a procedure of cross-coupling from 3-bromothiophene and sodium alkoxide in the presence of copper (I) iodide and N,N-dimethyl formamide.     

A Convenient Synthesis of 3-Methoxyphthalic Anhydride

Many antibiotics of the anthracycline family¹ possess structures for which 3-methoxyphthalic anhydride (1) would be a suitable synthon² in a total synthesis. A classic synthesis of (1) has employed 3-nitrophthalic acid³ but, in our hands, proceeded in low overall yield. Recent syntheses have utilized the Diels Alder reaction of dimethyl acetylenedicarboxylate (2) with 1-methoxy-1,3-cyclohexadiene,⁴ 1,4-diacetoxybutadiene,⁵ 2-acetoxyfuran,⁶ 2-methoxyfuran⁷ or furan⁸ to obtain 3-hydroxyphthalic acid or a derivative. We now wish to report a convenient Diels-Alder synthesis of (1) from 3-methoxy-2-pyrone (3).     

A Convenient Synthesis of 3-Benzoylindolizine-5-carbaldehydes

3-Benzoylindolizine-5-carbaldehydes (4a-f), which could be used as derivatization reagents for amino compounds in HPCE were synthesized based on the 1,3-dipolar cycloaddition of 1-phenacyl-2-(1,3-dioxolan-2-yl)pyridinium ylide with alkenes in the presence of TPCD.     

A New and Convenient Synthesis of 3-Hydroxychromones

An improved synthesis of 3-hydroxychromones is described.     

Convenient Synthesis of 3-Styrylphthalides

A convenient, high yield, two-step method is described for 3-styrylphthalides (3a - e) from 3-phenacylphthalides (1a - e)     

A Convenient Synthesis Of 3-Arylcoumarins From Arylacetonitriles

The condensation of salicylaldehydes with various arylacetonitriles catalyzed by anion-exchange resins such as Amberlite IRA 900, leads to the corresponding 3-arylcoumarins in good yields and selectivity.     

A Convenient Large Scale Synthesis of 2-Hydroxy-3-pinanone

A convenient large scale synthesis of 2-hydroxy-3-pinanone from readily available α-pinene has been developed. This two step method involves the diastereoselective dihydroxylation of α-pinene and subsequent oxidation of pinanediol to the hydroxyketone. The key advantages of this method, which allows access to large quantities of this important chiral auxiliary, are high yield and ease of operation.     

A Convenient Synthesis of 4-Amino-3-trimethylsilylalk-1-enes

Pinacol-E-1-trimethylsilyl-1-propene-3-boronate regiospecifically reacts with aldimines and ketimines to lead to 4-amino-3-trimethylsilylalk-1-enes with good yields.     

A Convenient Synthesis of Sendaverine

Sendaverine was isolated from Corydalis aurea willd by Manske and it was found to possess a tetrahydro-isoquinoline skeleton¹. The structural formula of the alkaloid has been established by the unambiguous synthesis by Kametani² and Miwako Mori et al.³     

A Convenient Synthesis of O-Alkyl-S-allenyl-Phosphoramidates

Ten title compounds 2a-j were synthesized by utilising mercuric (I) catalyzed thiono-thiolo rearrangement of O-propargyl-O-alkyl-pho-sphoramidothionates (1a-j) in HAc-NaAc buffer (PH=3.6). The yield of compounds 2a-e and 2f-j is 58–67% and 12–41%. This is the example of [3,3]-sigmatropic type rearrangement of 1,5-enyne system in thionop hosphoramidate chemistry.     

A Convenient Synthesis of Thioimidates

Thioimidates are useful reagents in preparative organic chemistry: for example, they are key intermediates for the synthesis of β-lactams bearing a thioether function at position 4, via an “acid chlorideimine” type reaction.¹     

A Convenient Synthesis of Tryptamines

Reaction of tosylmethyl isocyanide with substituted formyl indoles gave the nitrile with one more carbon atom. Hydrogenation of this nitrile afforded the corresponding tryptamine.     

A Convenient Synthesis of Protoanemonin

Abstract

A new convenient synthesis of protoanemonin (1) starting from 2-deoxy-d-ribose (3) is described. A key step in the sequence is the successive β- and δ-eliminations of 3,5-di-O-p-toluoyl-2-deoxy-d-ribono-1,4-lactone (6).     

A Convenient Synthesis of Triquinacene

We have recently reported the synthesis of a derivative of triquinacene (2,3-dihydrotriquinacen-2-one (14)⁴) from Thiele's acid (1). Although this new synthetic route is simple in concept, it suffers from a large number of chemical steps. We wish to communicate an important overall simplification of this synthetic scheme which makes readily available triquinacene (22) and several of its derivatives.     

A Convenient One-Step Gingerol Synthesis

Racemic 6-gingerol can be obtained in a one-pot reaction by hexanal addition to the dianion of zingerone at low temperature. Similarly, addition of octanal or decanal to the dianion provides 8-gingerol or 10-gingerol, respectively. Acid treatment of the gingerols allows for formation of the corresponding shogaols.     

A Convenient Synthesis of 3-Deoxy-D-gluco-2-octulosonate (D-gluco-KDO)

β-Lithiated acrylates have proven to be versatile pyruvate β-carbanion equivalents which are also useful in D-manno-KDO synthesis. The secondary amine adducts of acetylenedicarboxylate 4 display the same versatility, as demonstrated in this paper. However, on reaction with 2,3:4, 5-di-O-isopropylidene-D-arabinose 6, the diastereofacial selectivity is in favor of the gluco-isomer, thus leading with lithiated compounds 4A, preferentially to α-aminobutenolides 7-(g). The best results were obtained with the morpholine adduct of di-tert.-butyl acetylenedicarboxylate 4d which afforded the gluco-isomer 7d-(g) as an easily separable crystalline material. Its deamination and concomitant deisopropylidenation with trifluoroacetic acid provided the known α-hydroxy-butenolide 8b-(g), which was transformed via decarboxylation product 9-(g) to D-gluco-KDO 10-(g) thus concluding a convert four step synthesis of this compound via crystalline intermediates.