Short Syntheses of Gabosine I and Gabosine G from δ-d-Gluconolactone

A short synthesis of gabosine I (1) from δ-d-gluconolactone (3) in four steps, involving a one-pot TPAP oxidation−K2CO3-mediated intramolecular Horner−Wadsworth−Emmons (HWE) olefination as the key step, is described. Regioselective acetylation of the primary alcohol in gabosine I (1) then furnished gabosine G (2)

Total Synthesis of (+)-Quassin

A total synthesis of (+)-quassin from naturally occurring (S)-(+)-carvone is described. The total number of steps was 28, and the overall yield was about 2.6%. The synthetic strategy for the construction of the tetracyclic carbon framework was based on a C→ABC→ABCD ring annulation sequence, involving an aldol reaction, an intramolecular Diels−Alder reaction, and an intramolecular acylation as the key steps. Subsequent functionalization of ring A and ring C then afforded the target (+)-quassin

Facile and Enantiospecific Syntheses of (6<i>S</i>,7<i>R</i>)-6-Chloro-7-benzyloxy-, (7<i>S</i>)-Halo-, and (7<i>S</i>)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy

Total Synthesis of (+)-Quassin

A total synthesis of (+)-quassin from naturally occurring (S)-(+)-carvone is described. The total number of steps was 28, and the overall yield was about 2.6%. The synthetic strategy for the construction of the tetracyclic carbon framework was based on a C→ABC→ABCD ring annulation sequence, involving an aldol reaction, an intramolecular Diels−Alder reaction, and an intramolecular acylation as the key steps. Subsequent functionalization of ring A and ring C then afforded the target (+)-quassin

Facile and Enantiospecific Syntheses of (6<i>S</i>,7<i>R</i>)-6-Chloro-7-benzyloxy-, (7<i>S</i>)-Halo-, and (7<i>S</i>)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy

Enantiospecific Syntheses of (+)-Crotepoxide, (+)-Boesenoxide, (+)-β-Senepoxide, (+)-Pipoxide Acetate, (−)-<i>iso</i>-Crotepoxide, (−)-Senepoxide, and (−)-Tingtanoxide from (−)-Quinic Acid¹

A convenient strategy that is ideally suited for the construction of all the naturally occurring cyclohexane diepoxides and cyclohexene epoxides is described. The key intermediate 12, a 1,3-cyclohexadiene, has been prepared from (−)-quinic acid in 11 steps with 18% overall yield. Singlet oxygen photooxygenation of the 1,3-cyclohexadiene followed by rearrangement of the resultant endoperoxides with either cobalt-meso-tetraphenylporphyrin or trimethyl phosphite afforded enantiopure (+)-crotepoxide, (+)-boesenoxide, and (−)-iso-crotepoxide or (−)-senepoxide, (+)-β-senepoxide, (+)-pipoxide acetate, and (−)-tingtanoxide, respectively

Facile and Enantiospecific Syntheses of (6<i>S</i>,7<i>R</i>)-6-Chloro-7-benzyloxy-, (7<i>S</i>)-Halo-, and (7<i>S</i>)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy

Facile and Enantiospecific Syntheses of (6<i>S</i>,7<i>R</i>)-6-Chloro-7-benzyloxy-, (7<i>S</i>)-Halo-, and (7<i>S</i>)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy

Facile and Enantiospecific Syntheses of (6<i>S</i>,7<i>R</i>)-6-Chloro-7-benzyloxy-, (7<i>S</i>)-Halo-, and (7<i>S</i>)-Hydroxy-cocaine and Natural (−)-Cocaine from d-(−)-Ribose

First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from d-(−)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy

Intramolecular Direct Aldol Reactions of Sugar Diketones: Syntheses of Valiolamine and Validoxylamine G

A new and stereoselective intramolecular direct aldol reaction of diketones derived from carbohydrates has been developed to construct carbocycles with d-gluco-, d-galacto-, d-manno-, and l-ido-configurations. The stereochemical outcome of the aldol reaction of the diketone is dependent on the base used. Transformation of d-gluco-aldols readily affords valiolamine which also constitutes a formal synthesis of voglibose. Facile conversion of d-gluco-cyclohexanones into validoxylamine G has been achieved in 12 steps with 15.1% overall yield from d-glucose