I think, the first step should be a protonation at the furan 3- or 5-position with a subsequent attack of methanol on the carbonyl group that was formed followed by an acetal cleavage. (stackexchange.com)
The ketene acetal can be protonated and attacked by methanol at the carbonyl carbon, but that would be unproductive as there is no way of getting rid of one of the methyl groups on oxygen (unless we invoke a $\mathrm{S_N2}$ reaction on the methyl group with methanol acting as the nucleophile). (stackexchange.com)
Most monosaccharides form cyclic structures, which predominate in aqueous solution, by forming hemiacetals or hemiketals (depending on whether they are aldoses or ketoses) between an alcohol and the carbonyl group of the same sugar. (wikidoc.org)
Acyclic1
Cyclic acetals are more stable towards hydrolysis than acyclic ones, they are also much easier to make. (chemtube3d.com)
Oxygen2
So, in this reaction, the fragmentation step should be the reverse: the ejection of an enol oxygen from a (hemi)acetal. (stackexchange.com)
Since an "ether" is a functional group with an oxygen connected to two carbons, this also includes cyclic cases such as the five membered and three membered cyclic ethers below. (masterorganicchemistry.com)
Hydroxyl1
Glucose , for example, readily forms a hemiacetal linkage between its carbon-1 and the hydroxyl group of its carbon-5. (wikidoc.org)
Structures1
From the biological perspective, the key reactions involve addition of nucleophiles to the formyl carbon in the formation of imines (oxidative deamination) and hemiacetals (structures of aldose sugars). (wikipedia.org)
Aldoses1
These aldoses exist as hemiacetals, a sort of masked form of the parent aldehyde. (wikipedia.org)
Atoms1
This 1,5-hydride shift that was invoked seems to have a very strained transition state (the cyclic, planar system means that the "1" and "5" atoms are quite far apart) and with all due respect, I am quite skeptical as to whether it would really work. (stackexchange.com)
ETHERS1
Epoxides (oxiranes) are cyclic ethers that have unusually high reactivity due to ring strain (about 13 kcal/mol). (masterorganicchemistry.com)
Aldehyde2
2. The process as claimed in claim 2, wherein the aldehyde employed is an aliphatic or aromatic aldehyde having one or two aldehyde groups, hemiacetal or full acetal groups or mixtures thereof. (everypatent.com)
3. The process as claimed in claim 2, wherein a mixture of aldehyde and its full acetal and/or hemiacetal, in which the aldehyde content can be 1-99%, is employed. (everypatent.com)
What carbons bind to form the cyclic hemiacetal form of glucose? (flashcardmachine.com)
Formation5
10.Be able to write the detailed mechanism for acid and base catalyzed hemiacetal formation .Also, write the mechanism for the acid catalyzed conversion of a hemiacetal to an acetal. (utexas.edu)
Be familiar with cyclic acetal formation and the reason it is especially favorable. (utexas.edu)
The reaction produces two products, the acetal plus water, so the usually unfavourable entropy of acetal formation is not a factor. (chemtube3d.com)
Formation of hemiacetals and hemiketals . (wikidoc.org)
Readily1
Cyclic acetals are readily formed by the reaction of two molecules, a ketone and a diol. (chemtube3d.com)
Molecules1
It is the same with cyclic molecules - see how the second and third examples open to give linear products. (masterorganicchemistry.com)
Synthesis1
Also, be familiar with the use of acetals and cyclic acetals as protecting groups in synthesis. (utexas.edu)
Make2
Okay, Now, if you want to specifically make an a settle that not only has r r O R O r, but it's actually cyclic, meaning it forms a ring. (pearson.com)
1234 So I would need a dialogue to make my cyclic at the top. (pearson.com)
Single stereogenic center1
Answer: a Explanation: Meanwhile an epimer is a stereoisomer that is very different in configuration at any single stereogenic center, an anomer is a cyclic saccharide and an epimer that is different in configuration, specifically at the hemiacetal/acetal carbon, also known the anomeric carbon. (mocktestpro.in)
Carbon4
From the biological perspective, the key reactions involve addition of nucleophiles to the formyl carbon in the formation of imines (oxidative deamination) and hemiacetals (structures of aldose sugars). (wikipedia.org)
The anomer is a type of stereoisomer, differing in the configuration at the acetal/hemiacetal carbon atom (called also anomeric carbon). (knowswhy.com)
The carbon atom, where stereoisomerism occurs is the acetal/hemiacetal carbon (called also anomeric carbon). (knowswhy.com)
In nature, the linkages are _________ linkages, that's, acetal or ketal bonds involving the anomeric carbon of just one of the monosaccharides involved. (mocktestpro.in)
Bonds2
It's cyclic, conjugated, has 3 pi bonds and those pi bonds are all in the pi system. (masterorganicchemistry.com)
Explanation: A Haworth projection is a common way of formulating a structural formula to show the cyclic structure of monosaccharides with a simple 3-D perspective.The cyclic forms of carbohydrates are often represented by Haworth projections. (mocktestpro.in)
Form1
These aldoses exist as hemiacetals, a sort of masked form of the parent aldehyde. (wikipedia.org)