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Products from Reactions of Carbon Nucleophiles and Carbon

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Products from Reactions of Carbon Nucleophiles and Carbon 14C synthesis strategies, Chem 315/316 / Beauchamp 1 Products from reactions of carbon nucleophiles and carbon electrophiles used in the 14C Game and our course: Carbon and hydrogen nucleophiles Ph R Ph Al H N R Li R (MgBr) P Li AlH R Cu Li Na CN RCC Na Ph 4 Li Carbon 2 H C R organolithium organolithium cyanide acetylides 2 ylid Na BH4 diisobutylaluminium lithium diisopropy- electrophiles cuprates (LAH) o reagents reagents Wittig reagents hydride (DIBAH) amide (LDA), -78 C H C Br 3 not useful not useful 2 RX coupling nitrilesalkynes not useful alkyls alkyls not useful methyl RX reaction R Br not useful not useful 2 RX coupling nitriles alkynes not useful alkyls alkyls not useful primary RX reaction R 2 RX coupling nitriles alkyls not useful E2 not useful alkyls not useful not useful reaction R Br secondary RX O 1o ROH 1o ROH 1o ROH 1o ROH not useful 1o ROH o not useful not useful 1o ROH 1 ROH ethylene oxide nitriles alkynes O o o o o o o 2 ROH 2 ROH 2 ROH 2 ROH 2o ROH 2 ROH 2 ROH not useful not useful E2, make nitriles alkynes allylic alcohols propylene oxide O o 3 ROH 3o ROH o 3o ROH o not useful o 3o ROH not useful E2, make 3 ROH 3 ROH 3 ROH allylic alcohols nitriles alkynes isobutylene oxide O o o specific methanol methanol C 1 ROH 1 ROH not used cyanohydrin 1o ROH not useful not useful in our course alkenes H H alkynes methanal O specific o enolate o o cyanohydrin o 1 ROH o C 2 ROH 2 ROH not useful 2 ROH alkenes 1 ROH not useful chemistry R H alkynes simple aldehydes O cyanohydrin o unless specific o enolate C 3 ROH 3o ROH o 2o ROH 2 ROH not useful sterically 3 ROH alkenes not useful chemistry R R hindered simple ketones alkynes O o o 3 ROH 3 ROH not used enolate C R not useful not useful 1o ROH not useful aldehydes (Nu: twice) (Nu: twice) not useful in our course chemistry R O simple esters O ketones acid/base acid/base acid/base acid/base acid/base enolate C use 2 equivalents acid/base acid/base no net rxn no net rxn no net rxn not useful no net rxn no net rxn no net rxn chemistry R OH no net rxn HCN = danger simple (B: once carboxylic acids Nu: once) O C o o 3 ROH 3 ROH not useful o o E2, make ketones not useful not useful 1 ROH 1 ROH aldehydes ketenes R Cl (Nu: twice) (Nu: twice) simple acid chlorides o R C N 1 amines aldehydes ketones simple nitriles ketones enolate not useful not useful not useful not useful (also amines not useful chemistry RCONR' (also aldehydes 2 ketones ketones 3o amides from amides) from 3o amides) ketones O CO use 2 equivalents carboxylic not useful not useful carboxylic not useful not useful not useful not useful not useful (B: once acids acids carbon dioxide Nu: once) O conjugate C o o not useful 3 ROH 3 ROH conjugate addition not useful alcohols alcohols not useful R addition α,β-unsaturated ketones + WK = normal workup to neutralize the reaction conditions. For the basic reactions (like above) above this would require mild acid neutralization (H3O ). NR = no reaction or no productive result or not emphasized Z:\classes\316\special handouts\316 Syn & C14 strategies.doc 14C synthesis strategies, Chem 315/316 / Beauchamp 2 * nucleophile (Nu) = ? In our course every carbon-carbon bond made C C with asterisked carbon must be made with a electrophile (E) = ? nucleophile/electrophile reaction. OH OH OH E E OH * * * * C C C C CC C C * C C Nu E E Nu Nu clue: COH group could have been an electrophilic Nu C=O group (aldehyde or ketone) + nucleophilic clue: COH group could have been an electrophilic C=O Grignard or lithium reagent. group (ester) + nucleophilic Grignard or lithium reagent (2x). OH E E OH H E E H * * C C C C *C C C* C O O O O Nu Nu Nu Nu clue: COH group could have been an electrophilic C=O group clue: CHO (aldehyde) group can be made from (carbon dioxide) + nucleophilic Grignard or lithium reagent. nucleophilic Grignard or lithium reagents + electrophilic dimethylformamide (DMF). OH O O O O O *C C C O electrophiles = C C C C C H H R H R R R OR Nu E O clue: COH group could have been an electrophilic Mg or 2Li epoxide group + nucleophilic Grignard or lithium nucleophiles = R Br R (MgBr) or Li reagent. O O O E O N * C C C C C C electrophiles = R OH R NR' R Cl R R 2 carboxylic nitriles3o amides acid chlorides Nu acids clue: C=O group could have been 2 equivalents a (nitrile + Grignard or lithium reagent), R Cu R o nucleophiles = (MgBr) or Li a ( 3 amide + Grignard or lithium reagent), R R Li R Li an (acid chloride + cuprate) or Mg and Li organometallics cuprates organolithium a (carboxylic acid + 2 eqs. of R-Li). reagents O α β α α O O β O α C β β electrophiles = * C R OR α,β-unsaturated C=O Nu clue: C=O group could have been an electrophilic α,β-unsaturated cuprate R Cu R C=O (+ nucleophilic cuprate = conjugate addition). nucleophiles = Li Z:\classes\316\special handouts\316 Syn & C14 strategies.doc 14C synthesis strategies, Chem 315/316 / Beauchamp 3 Carbon skeletons from C1 – C7 aba b c CH4 C1 skeleton C2 skeleton C3 skeleton C4 skeletons C5 skeletons a b c d e C6 skeletons d a b c e f g h i C7 skeletons Seven carbon skeleton – “isomer c” with variable 14C labels 2 4 6 * * 1 3 5 * * C2-star 7 C1-star C3-star C4-star * * C7-star no 14C label C5-star C6-star * Seven carbon skeleton - “isomer c” with variable “OH”, no 14C labels 2 6 OH OH 4 OH HO 3 5 1 7 C1-OH C2-OH C3-OH C4-OH OH C5-OH OH C6-OH C7-OH OH Seven carbon skeleton – “isomer c” with 14C label on first carbon (C1-star) and variable “OH” 2 6 OH OH 4 OH HO * 3 5 * 1 * * 7 C1-star, C1-OH C1-star, C2-OH C1-star, C3-OH C1-star, C4-OH * * * OH OH C1-star, C5-OH C1-star, C6-OH C7-star, C1-OH OH Z:\classes\316\special handouts\316 Syn & C14 strategies.doc 14C synthesis strategies, Chem 315/316 / Beauchamp 4 The following carbon skeletons represent parts of structures that can be made with or without 14C labeled positions. C1 – C4 carbon skeletons are all shown, with “*” to indicate the location of any 14C label. In structures with 5 carbon atoms, or more, the first structure drawn represents the parent skeleton and the second structure shows all of the different positions that a single 14C label could be inserted (a number indicates each different possibility). "X" represents a simple functional group or a point of attachment in a functional group pattern that could have more than one carbon portion. (See example page with several examples of functional group patterns that could have 2 or more branches.) Synthetic targets can be randomly generated by drawing out a number for the carbons in the skeleton (1-7), then picking a random pattern, then picking a random isomer with or without a 14C label. This can be done once, twice or 3 times for each branch in the selected functional group pattern (which can also be picked at random). The possibilities are effectively endless for organic synthesis problems (there are about 420 skeletal patterns, including 14C labels). These problems are relatively straight forward because there is only 1 functional group. More than one functional group may require protection/deprotection steps and the difficulty of such synthetic problems can rapidly go up. Some patterns may have limitations due to steric crowding. (X = OH, Br, OR, O2CR, NH2, CN, CCR and many other possibilities) 1 carbon 2 carbons 3 carbons 4 carbons pattern 1 pattern 2 pattern 4 pattern 1 pattern 3 pattern 2 1 1 1 1 X 1 3 X 1 1 X * 4 X X H3C X 2 * 2 X * * * 1 2 2 2 2 X 2 X * X X 3 * X X H C X * X 3 X X * 3 X 2 4 * 3 5 * * * 3 4 * X X 3 X 3 * * X * * X 5 X 4 * X X X * X * X 5 carbons: 1 = parent skeleton without any 14C label, numbers = skeleton location with a 14C label at that position (for reference in synthesis problems) pattern 1 pattern 2 pattern 3 pattern 4 pattern 5 pattern 6 pattern 7 pattern 8 1 = parent skeleton 1 X 1 1 1 1 1 X 1 X X X X X 3 5 X 3 6 X 2 4 6 2 4 X 5 3 2 4 5 2 4 6 5 3 2 4 3 2 4 3 5 2 3 X X 3 5 4 X X 2 4 X X 6 carbons: 1 = parent skeleton without any 14C label, numbers = skeleton location with a 14C label at that position (for reference in synthesis problems) pattern 1 pattern 2 pattern 3 pattern 4 pattern 5 pattern 6 pattern 7 1 = parent skeleton 1 1 1 X 1 1 1 X X X X X 3 5 7 7 X X 3 5 7 2 4 6 2 4 6 X 5 5 5 7 2 3 2 4 6 2 4 6 3 5 2 4 6 3 3 X X 4 6 X 3 5 X X 2 4 6 pattern 8 pattern 9 pattern 10 pattern 11 pattern 12 pattern 13 pattern 14 pattern 15 1 1 1 X 1 1 X 11 1 X X X X X X X X 3 3 5 2 3 2 4 4 5 6 2 4 6 4 5 4 4 4 3 3 5 2 3 5 3 3 5 2 4 2 2 2 6 X 5 X 5 6 X X 7 7 X X Z:\classes\316\special handouts\316 Syn & C14 strategies.doc 14C synthesis strategies, Chem 315/316 / Beauchamp 5 7 carbons: 1 = parent skeleton without any 14C label, numbers = skeleton location with a 14C label at that position (for reference in synthesis problems) pattern 1 pattern 2 pattern 3 pattern 4 pattern 5 1 = parent skeleton 1 11 X 1 X X X 3 5 7 X 8 2 4 6 8 X X X 3 2 2 3 5 7 2 6 8 4 5 7 X 2 4 6 8 3 5 7 5 4 6 3 4 X pattern 6 pattern 8 pattern 7 pattern 9 pattern 10 pattern 11 X 1 1 11 1 1 X X X X X X X 3 5 7 5 5 7 3 7 4 6 6 2 4 6 4 6 3 3 5 7 3 5 7 4 2 4 2 2 2 6 3 5 7 X 4 X 2 6 X 8 X pattern 12 pattern 13 pattern 14 pattern 15 pattern 16 pattern 17 1 X 1 X 1 X 1 X 1 1 X X X X 3 X X 3 5 2 4 4 2 6 5 7 4 6 4 6 3 5 3 7 3 5 7 7 7 5 3 5 7 2 2 6 2 4 6 2 4 6 8 8 8 8 8 X 8 X pattern 19 pattern 18 pattern 20 pattern 21 pattern 22 pattern 23 pattern 24 1 1 1 1 X 1 1 X 1 X X 7 X X X 8 X X 3 5 3 4 6 2 2 5 4 6 3 5 3 5 3 5 3 4 6 4 5 2 6 3 2 4 6 4 6 X 5 2 X 2 X 2 4 6 X X 7 7 7 pattern 25 pattern 26 pattern 27 pattern 28 pattern 29 pattern 30 pattern 31 X 1 11 1 1 1 1 X X X X X X 7 X 4 3 5 3 5 6 2 2 4 4 6 2 6 3 4 5 3 5 3 3 4 2 4 3 5 6 2 4 6 2 7 5 2 X X 6
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