3 research outputs found
Carbasugar Synthesis via Vinylogous Ketal: Total Syntheses of (+)-MK7607, (−)-MK7607, (−)-Gabosine A, (−)-Epoxydine B, (−)-Epoxydine C, <i>epi</i>-(+)-Gabosine E and <i>epi</i>-(+)-MK7607
Carbasugars,
the carbocyclic analogues of sugars, constitute an important class
of natural products with more than 140 members known and have attracted
much attention due to their diverse biological activities like anticancer,
antibacterial, herbicidal, and various enzyme inhibitory activities.
As many carbohydrates are involved in various cellular signaling pathways,
there is great interest in synthesis and biological exploration of
carbasugars. Herein, we have developed a methodology to install an α,β-unsaturated
aldehyde functionality on different inositols and derivatives by vinylogous
elimination of the O-protecting group under mildly acidic condition.
We have illustrated the versatility and utility of our methodology
by the total syntheses of seven carbasugars viz. (−)-MK7607,
(−)-gabosine A, (−)-epoxydine B, (−)-epoxydine
C, (+)-MK7607, 1-<i>epi</i>-(+)-MK7607 and 1-<i>epi</i>-(+)-gabosine E
Vinylogy in Orthoester Hydrolysis: Total Syntheses of Cyclophellitol, Valienamine, Gabosine K, Valienone, Gabosine G, 1-<i>epi</i>-Streptol, Streptol, and Uvamalol A
C7-cyclitols represent an important
category of natural products
possessing a broad spectrum of biological activities. As each member
of these compounds is structurally unique, the usual practice is to
synthesize them individually from appropriate polyhydroxylated chiral
pools. We have observed an unusual vinylogy in acid mediated hydrolysis
of enol ethers of <i>myo</i>-inositol 1,3,5-orthoesters
giving a synthetically versatile polyhydroxylated cyclohexenal intermediate.
We have exploited this unprecedented reaction for developing a general
strategy for the rapid and efficient syntheses of several structurally
diverse natural products of C7-cyclitol family. We have made an appropriately
protected advanced intermediate 25 in five steps from the cheap and
commercially available <i>myo</i>-inositol, and this common
intermediate has been used to synthesize eight natural products in
racemic form. We could synthesize (±)-cyclophellitol in seven
steps, (±)-valienamine in five steps, (±)-gabosine I in
five steps, (±)-gabosine G in six steps, (±)-gabosine K
in three steps, (±)-streptol in six steps, (±)-1-<i>epi</i>-streptol in two steps, and (±)-uvamalol A in five
steps from this intermediate
Vinylogy in Orthoester Hydrolysis: Total Syntheses of Cyclophellitol, Valienamine, Gabosine K, Valienone, Gabosine G, 1-<i>epi</i>-Streptol, Streptol, and Uvamalol A
C7-cyclitols represent an important
category of natural products
possessing a broad spectrum of biological activities. As each member
of these compounds is structurally unique, the usual practice is to
synthesize them individually from appropriate polyhydroxylated chiral
pools. We have observed an unusual vinylogy in acid mediated hydrolysis
of enol ethers of <i>myo</i>-inositol 1,3,5-orthoesters
giving a synthetically versatile polyhydroxylated cyclohexenal intermediate.
We have exploited this unprecedented reaction for developing a general
strategy for the rapid and efficient syntheses of several structurally
diverse natural products of C7-cyclitol family. We have made an appropriately
protected advanced intermediate 25 in five steps from the cheap and
commercially available <i>myo</i>-inositol, and this common
intermediate has been used to synthesize eight natural products in
racemic form. We could synthesize (±)-cyclophellitol in seven
steps, (±)-valienamine in five steps, (±)-gabosine I in
five steps, (±)-gabosine G in six steps, (±)-gabosine K
in three steps, (±)-streptol in six steps, (±)-1-<i>epi</i>-streptol in two steps, and (±)-uvamalol A in five
steps from this intermediate