S configuration?

[SaintJude]

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So this molecule is an an s configuration. Why? How do I know the hydrogen is "in the back" if its stereochemistry is not shown. Sorry for this "basic question" but I gotta ask.

View attachment Picture 10.png

 

[Ssina]

forget that methode and use the this:

stick your thumb where the H is (or the lowest priority if not H/#4), then wrap your fingers from priority 1 to 2 to 3.... if you used your right hand then it's R and if you used your left hand it's S

so here thumb up and since group 1 is in the back (C=C) you have to use your left hand... then fingers go from C=C to CH2Ch3 then to CH3... so it's S

(Credit: TBR methode)

 

[Erythropoietin]

when H is in the plane far away from the back group, take whatever you observe as it is, which is S

 

[SaintJude]

forget that methode and use the this:

stick your thumb where the H is (or the lowest priority if not H/#4), then wrap your fingers from priority 1 to 2 to 3.... if you used your right hand then it's R and if you used your left hand it's S

so here thumb up and since group 1 is in the back (C=C) you have to use your left hand... then fingers go from C=C to CH2Ch3 then to CH3... so it's S

(Credit: TBR methode)

😱 That. Is. Amazing.

Thank you!

 

[SaintJude]

O my goodness. How did Kaplan not make me aware of this..or my teachers?! I feel so compelled to let others know of this...here is the google link to the original paper that has lots of good practice using the right/hand left hand rule.

http://goo.gl/SUYmI

 

[Erythropoietin]

cool article

 

[DocGodfather]

O my goodness. How did Kaplan not make me aware of this..or my teachers?! I feel so compelled to let others know of this...here is the google link to the original paper that has lots of good practice using the right/hand left hand rule.

http://goo.gl/SUYmI

Cool thanks for the extra notes on chirals. I'm sure I'll need refreshers between now and next January.

 

[Ssina]

loool my reaction, precisely!

Much faster this way, vs. trying to imagine H pointing to the back or if you rotate 60 degrees change from R to S.... blah blah!! you don't have to bother with that anymore, you might look like a fool during the test twisting your hand around your head/back, but makes you look more legit/onto something 🤣

regardless of where they got it from, I can say that through this process (rather unconsciously), I have officially converted to TBRism!
cool link btw!

 

[MedPR]

So this molecule is an an s configuration. Why? How do I know the hydrogen is "in the back" if its stereochemistry is not shown. Sorry for this "basic question" but I gotta ask.

View attachment 18405

Forget all other methods, this one is the easiest.

When the lowest sub isn't in back, just switch it with whatever is in back. Don't worry about rotation or anything, just redraw it with the lowest sub in back.

Now figure out if your new structure is R or S. The configuration of the original is the opposite of whatever you come up with.

 

[Hexon]

forget that methode and use the this:

stick your thumb where the H is (or the lowest priority if not H/#4), then wrap your fingers from priority 1 to 2 to 3.... if you used your right hand then it's R and if you used your left hand it's S

so here thumb up and since group 1 is in the back (C=C) you have to use your left hand... then fingers go from C=C to CH2Ch3 then to CH3... so it's S

(Credit: TBR methode)

that is a cool method; almost makes me angry how much i've suffered doing the whole tetrahedral diagram BS.

thanks bro