<p>for 22b, what does the meoh do to the sugar?</p>
<p>youknow shooting myself in the foot would take about 2 hours of surgery. same as taking this midterm.</p>
<p>MeOH, H+ protects the anomeric hydroxy group from reacting with PCC by converting the hydroxy group into a methoxy group.</p>
<p>but you can’t just use acetone? (kinda forgot the problem, but I guess in general?</p>
<p>Acetone works if you have TWO hydroxy groups (that are cis to each other) and the hydroxy on the anomeric carbon in 22b is all by itself so acetone wont work.</p>
<p>Also just FYI MeOH, H+ only works on the hydroxy group on anomeric carbons.</p>
<p>alright gotcha. thanks a lot. my notes had meoh but i didn’t know what the hell i was writing.</p>
<p>On 298 (first box), where did the other 2 stereoisomers come from… I thought the molecule started w/ optical activity, so how is the C w/ the Ph group a new stereocenter?</p>
<p>This is a 1,2 addition of CN, right? :)</p>
<p>@cb: as opposed to the other hydroxy groups right? cuz nothing can happen? only at the anomeric C can electrons move to the O next to it?</p>
<p>@sa: the stereochemistry on the left isn’t defined so it’s a stereocenter, so you have to take that into account when it asks you to draw stereoisomers. and yes, 1,2.</p>
<p>Yeah the reason it works for the anomeric is because the oxygen is used to kick off the water after it was protonated and the other hydroxy group can’t because the oxygen is to far away to react with it.</p>
<p>nice, thanks for that. btw do you guys think the carb and nomenclature section is easier than it should be? reminds me of last midterm when the practice nomenclature problems were cake and then the ones on the real test were hard as crap.</p>
<p>lol probably. but they’re frankly kinda easy-ish to remember. i can’t keep my reagents straight right now though. like everything is being used for everything else. </p>
<p>why are there no base conditions for acetals?
is the oh just blocking another from attaching?</p>
<p>it just doesn’t work. what are you going to deprotonate? what electrons are you going to move around? you can’t. try deprotonating the OH hanging off the anomeric C and see if anything happens. you won’t be able to do anything.</p>
<p>I think it’s because the OH would react and it would become a hemiacetal, to get the acetal you need like both MeOH groups to be attached to it, no OHs.</p>
<p>alright that’s where i got stuck and i thought i was doing something wrong. ahah</p>
<p>how do we actually name a hydrazone or an oxime?</p>
<p>is the test at 7 or 7:30
i’m freaking out =/</p>
<p>test was lolbrutal. for me definitely.</p>
<p>yup. me too. way way worse than first midterm? can average really be > 60/150 cuz i don’t think so.</p>
<p>I knew going in i wasn’t prepared. I came out confirming I wasn’t prepared</p>