Appendix C — Common Reaction Summary (by mechanism f... | Organic Chemistry

Organized by mechanism family, not by functional group — matching the book's philosophy. Use this as a desk reference during problem sets. For each entry — substrate, reagent, key conditions, stereochemistry, regiochemistry, chapter cross-reference, and the most common pitfall.

Arrow notation — "A → B" means starting material → product. "[reagent / conditions]" sits over the arrow. Stereochem and regio cues in italics.

Family 1 — Nucleophilic Substitution

SN2

R-LG + Nu⁻ → R-Nu + LG⁻ (inversion at C, concerted)

Aspect	Detail
Substrate	methyl > 1° > 2°; 3° does NOT react
Nucleophile	strong: HO⁻, RO⁻, RS⁻, CN⁻, N₃⁻, NH₃, I⁻, RC≡C⁻
LG	I⁻ > Br⁻ > Cl⁻ ≫ F⁻; OTs, OMs, OTf excellent
Solvent	polar aprotic (DMSO, DMF, acetone, MeCN) accelerates
Stereochem	Walden inversion, 100%
Regiochem	only at carbon bearing LG
Rate law	rate = k[R-LG][Nu]
Chapter	10
Pitfall	β-branching kills the rate (neopentyl R-LG is unreactive)

SN1

R-LG → R⁺ + LG⁻ → R-Nu (2 steps, planar cation intermediate)

Aspect	Detail
Substrate	3° > 2° (with stabilization) > benzylic, allylic; 1° and methyl do not
Nucleophile	weak: H₂O, ROH, RCOOH
LG	same as SN2
Solvent	polar protic (H₂O, ROH) stabilizes cation
Stereochem	racemization (with slight inversion bias)
Regiochem	possible rearrangement (H, Me shift to more-stable cation)
Rate law	rate = k[R-LG]
Chapter	11
Pitfall	Always check for rearrangement when 2° next to 3°

SNAr — Nucleophilic Aromatic Substitution

Ar-LG (with EWG ortho/para) + Nu⁻ → Ar-Nu + LG⁻ (addition-elimination via Meisenheimer)

Aspect	Detail
Substrate	aryl halide with strong EWG ortho or para to LG (NO₂, CN, C=O)
LG order	F > Cl > Br > I (opposite of SN2 — addition is rate-limiting)
Nucleophile	RO⁻, RNH₂, RS⁻, malonate anion, hydroxide
Stereochem	n/a (aromatic)
Chapter	23
Pitfall	Without strong EWG, won't work; consider benzyne instead

Benzyne mechanism

Ar-X + strong base (NaNH₂) → benzyne intermediate + Nu → Ar-Nu (mixture of regiochemistry)

Aspect	Detail
Conditions	NaNH₂ / NH₃(l), or t-BuOK
Stereochem	mix at the two carbons of the former triple-bond
Chapter	23
Pitfall	Use only when SNAr/SN1/SN2 are all unavailable

Family 2 — Elimination

E2

H-Cβ-Cα-LG + B⁻ → C=C + BH + LG⁻ (concerted, anti-periplanar)

Aspect	Detail
Substrate	1°, 2°, 3° all work
Base	strong: NaOH, NaOR, LDA, NaNH₂
Geometry	H and LG must be anti-periplanar (180°)
Regiochem	Zaitsev (more-substituted alkene) with small base; Hofmann (less-substituted) with bulky base (t-BuOK, LDA)
Stereochem	stereospecific — fixed alkene geometry from substrate
Rate law	rate = k[R-LG][B]
Chapter	12
Pitfall	Ring systems: must have axial H and axial LG (cyclohexane)

E1

R-LG → R⁺ → C=C + H⁺ (2 steps, same cation as SN1)

Aspect	Detail
Substrate	3°, benzylic, allylic
Base	weak (solvent itself)
Conditions	heat
Regiochem	Zaitsev
Stereochem	major alkene typically E
Chapter	12
Pitfall	Competes with SN1; high T favors elimination

E1cb

HCα-C(=O) → ⁻Cα-C(=O) → C=C + LG⁻ (deprotonation first, then LG leaves)

Aspect	Detail
Substrate	β-LG with acidic α-H (e.g., β-hydroxy ketone losing H₂O)
Base	mild (carbonate, amine)
Conditions	the cation pathway is impossible; carbanion is stabilized
Chapter	12, 28 (aldol condensation step)
Pitfall	Easy to miss — looks like E2 but goes the other way

Cope elimination (amine N-oxide)

R-CH(NR'₂⁺-O⁻)-CH₂-R'' → alkene + R'₂NOH

Aspect	Detail
Conditions	heat (no base needed)
Geometry	syn-periplanar
Stereochem	gives Hofmann alkene
Chapter	23

Hofmann elimination

R-CH₂-CH₂-NMe₃⁺ → alkene + NMe₃ (after Hofmann exhaustive methylation)

Aspect	Detail
Conditions	heat with Ag₂O / OH⁻
Regiochem	Hofmann (less-substituted alkene)
Chapter	23

Family 3 — Electrophilic Addition to Alkenes

Reaction	Reagent(s)	Stereochem	Regiochem	Product	Ch	Pitfall
HX addition	HCl, HBr, HI	mix (Markov via cation)	Markovnikov	alkyl halide	15	Rearrangement (2°→3°)
Radical HBr	HBr + ROOR / hν	anti-Markovnikov	anti-Mark	1° bromide	18	Only HBr; HCl/HI do not work
Acid-cat. hydration	H₃O⁺ (H₂SO₄/H₂O)	mix, racemic	Markovnikov	alcohol	16	Rearrangement
Oxymercuration-demerc.	(1) Hg(OAc)₂, H₂O; (2) NaBH₄	anti addn, no rearr	Markovnikov	alcohol	16	Hg toxicity
Hydroboration-ox.	(1) BH₃/THF or 9-BBN; (2) H₂O₂/NaOH	syn	anti-Markovnikov	1° alcohol	16	Sterics matter; choose BH₃ vs 9-BBN
Halogenation	Br₂ or Cl₂	anti (via halonium)	both C get X	vicinal dihalide	16	F₂ uncontrollable; I₂ doesn't add
Halohydrin formation	Br₂/H₂O or NBS/H₂O	anti	OH at more-sub C (Markov)	1,2-bromohydrin	16	Bromonium opening rules regio
Epoxidation	mCPBA, DMDO, peroxytrifluoroacetic	syn, concerted	n/a	epoxide	16	mCPBA classic for alkene
Dihydroxylation	OsO₄ / NMO; or KMnO₄ cold dilute	syn	n/a	cis-diol	16	OsO₄ toxic; use catalytic
Anti dihydroxylation	(1) RCO₃H; (2) H₃O⁺	anti	n/a	trans-diol	16	Two-step
Ozonolysis (reductive)	O₃ then Me₂S, Zn/AcOH, PPh₃	cleavage	n/a	aldehydes/ketones	16	"Reductive" workup gives aldehydes intact
Ozonolysis (oxidative)	O₃ then H₂O₂	cleavage	n/a	carboxylic acids/ketones	16	Aldehyde → COOH
Hydrogenation	H₂ / Pd/C, Pt, Ni	syn	n/a	alkane	16	Reduces other π bonds too
Catalytic hydrogen.	H₂ / Lindlar (Pd-CaCO₃-Pb)	syn	stops at alkene	alkene from alkyne	17	Selective
Carbene addition	:CH₂ (from CH₂I₂/Zn-Cu, Simmons-Smith)	syn, retains alkene config	n/a	cyclopropane	16	Stereospecific

Markovnikov rule — H goes to the carbon with more H (the less-substituted one); the new bond at the more-substituted carbon is the carbon that better stabilizes positive charge.

Family 4 — Addition to Alkynes (Ch 17)

Reaction	Reagents	Result	Regiochem	Stereochem
1 eq HX	HBr	vinyl halide	Markov	(mix)
2 eq HX	HBr (excess)	gem-dihalide	Markov	—
Acid hydration	H₂O / H₂SO₄ / HgSO₄	methyl ketone (from terminal)	Markov	—
Hydroboration-ox.	(1) disiamylborane or 9-BBN; (2) H₂O₂	aldehyde (from terminal)	anti-Mark	—
H₂, Lindlar	H₂ / Pd-CaCO₃-Pb	cis-alkene	n/a	syn (cis)
Dissolving metal	Na / NH₃(l)	trans-alkene	n/a	trans (anti)
Full hydrogenation	H₂, Pd/C (excess)	alkane	n/a	n/a
Halogenation	X₂ (1 or 2 eq)	(E)-1,2-dihaloalkene or tetrahalide	—	trans (anti)

Alkynide chemistry

RC≡C-H + NaNH₂ → RC≡C⁻Na⁺ (acetylide; pKa 25 → easily deprotonated) RC≡C⁻ + R'X (1° only) → RC≡C-R' (SN2) RC≡C⁻ + R'CHO → RC≡C-CH(OH)R' (propargyl alcohol)

Aspect	Detail
Base	NaNH₂ in NH₃(l), or n-BuLi
Electrophile	1° R-X (SN2); also aldehydes, ketones, epoxides
Pitfall	2°/3° R-X gives E2 instead
Chapter	17

Family 5 — Aromatic Chemistry (Chs 20-22)

Electrophilic Aromatic Substitution (EAS)

Ar-H + E⁺ → Ar-E + H⁺ (via arenium / Wheland intermediate)

Reaction	Electrophile generation	Product	Notes	Ch
Halogenation	Cl₂/FeCl₃, Br₂/FeBr₃; I₂/HNO₃	Ar-X	I₂ alone fails	21
Nitration	HNO₃ + H₂SO₄ → NO₂⁺	Ar-NO₂	Reduce to NH₂ with Sn/HCl or H₂/Pd	21
Sulfonation	SO₃ in H₂SO₄	Ar-SO₃H	Reversible — can dilute to remove	21
Friedel-Crafts alkylation	R-X + AlCl₃ → R⁺	Ar-R	Rearrangement, polyalkylation	21
Friedel-Crafts acylation	R-COCl + AlCl₃ → R-CO⁺	Ar-COR	Clean; reduce CO → CH₂ via Wolff-Kishner or Clemmensen	21

Directing effects (Ch 22)

Substituent class	Examples	Activator/Deactivator	Directs
Strong activators	-NH₂, -NHR, -NR₂, -OH, -OR	act	o,p
Moderate activators	-NHCOR, -OCOR	act	o,p
Weak activators	-R (alkyl), -Ar	act	o,p
Halogens	-F, -Cl, -Br, -I	deact (mild)	o,p (special)
Weak deactivators	-CHO, -COR, -COOH, -COOR, -CONH₂	deact	m
Strong deactivators	-NO₂, -CN, -SO₃H, -NR₃⁺, -CF₃	deact	m

Side-chain reactions on alkylbenzenes

Reaction	Reagent	Product	Notes	Ch
Benzylic bromination	NBS, hν or peroxide	benzylic Br	radical	18
Benzylic oxidation	KMnO₄, hot or Cr(VI)	Ar-COOH	strips alkyl to COOH (regardless of length)	22
Benzylic reduction	H₂, Pd; PhCH₂-OR/X cleaved	Ar-H or Ar-CH₃	hydrogenolysis of Bn ethers	22

Nucleophilic Aromatic Substitution (SNAr) — see Family 1.

Benzyne — see Family 1.

Birch reduction

Ar-H + Na/NH₃(l), ROH → 1,4-cyclohexadiene

Aspect	Detail
EDG (e.g., -OR)	sits at non-reduced sp² position
EWG (e.g., -COOH)	sits at reduced sp³ position
Chapter	22

Family 6 — Carbonyl Addition (Ch 25)

R-C(=O)-R' + Nu → R-C(O⁻)(Nu)-R' → tetrahedral intermediate → product

Nu / reagent	Product	Conditions	Stereochem	Chapter
HCN, KCN	cyanohydrin RC(OH)(CN)R'	catalytic base	mix	25
H₂O	gem-diol (mostly hydrate of aldehyde)	acid or base cat	—	25
ROH (1 eq) + H⁺	hemiacetal	acid cat	—	25
ROH (2 eq) + H⁺	acetal R₂C(OR')₂	acid cat, remove H₂O	—	25
1,2-diol + H⁺	cyclic acetal (protecting group)	acid cat	—	25
Primary amine RNH₂	imine R₂C=NR'	acid cat (pH 4-5 optimal)	E preferred	25
Secondary amine R₂NH	enamine R₂C=CR'-NR'₂	acid cat	—	25
Hydrazine NH₂NH₂	hydrazone	—	—	25
2,4-DNP	2,4-DNP-hydrazone (orange precipitate)	—	—	25 (classic test)
Hydroxylamine NH₂OH	oxime	—	E preferred	25
NaBH₄	1°/2° alcohol (reduces aldehyde, ketone; not ester/amide)	MeOH or EtOH	—	25, 36
LiAlH₄	1°/2° alcohol (reduces ALL: ester, amide, nitrile, COOH)	dry ether, then quench	—	25, 36
DIBAL-H (1 eq, −78°C)	aldehyde from ester or nitrile	toluene, −78°C	—	26
Grignard RMgX	alcohol; methanal → 1°, aldehyde → 2°, ketone → 3°	dry ether, then H₃O⁺	mix	25
Organolithium RLi	alcohol (similar to Grignard)	dry, low T	mix	25
Wittig Ph₃P=CR₂	alkene RR'C=CR₂	salt-free conditions for Z; stabilized ylide → E	(E or Z controlled)	25
Horner-Wadsworth-Emmons (HWE)	(RO)₂P(O)CH₂R + base + aldehyde → E-alkene	NaH or LiHMDS	E selective	25
α-Silyl carbanion (Peterson)	R₃Si-CR'₂⁻ + ketone → alkene	acid or base workup gives E or Z	controlled	25

Reactivity — aldehyde > ketone (steric and electronic). Cyclohexanone > acyclic ketone.

Family 7 — Acyl Substitution (Ch 26)

R-C(=O)-LG + Nu → R-C(=O)-Nu + LG⁻ (addition-elimination via tetrahedral intermediate)

Reactivity order — acid chloride > anhydride > ester ≈ COOH > amide. Each can be converted "down the ladder" easily; going "up" requires activation.

From acid chloride R-COCl

Nu	Product	Conditions
H₂O	RCOOH	—
ROH	ester RCOOR	base (pyridine, Et₃N) to neutralize HCl
R'NH₂	amide RCONR'H	base (Schotten-Baumann)
R'COO⁻	anhydride RCO-O-COR'	—
(R')₂CuLi (Gilman)	ketone RCOR'	low T, single addition
LiAlH(OtBu)₃ (DIBAL works too)	aldehyde RCHO	controlled stop
LiAlH₄	1° alcohol RCH₂OH	full reduction

From ester R-COOR'

Nu	Product	Conditions
H₂O / H⁺	RCOOH + R'OH	reversible (Fischer)
H₂O / OH⁻ (saponification)	RCOO⁻ + R'OH	irreversible
R''OH / H⁺	transesterification	reversible
R''NH₂	amide RCONR''H + R'OH	—
R''MgX (2 eq)	3° alcohol	adds twice (cannot stop at ketone)
DIBAL-H (1 eq, −78°C)	aldehyde RCHO	careful
LiAlH₄	1° alcohol RCH₂OH	full
Hydrazine	hydrazide

From amide R-CONR'₂

Nu	Product	Conditions
H₂O / H⁺ or OH⁻	RCOOH + HNR'₂	harsh — amides are tough
LiAlH₄	amine RCH₂NR'₂	reduces C=O fully; the N stays
POCl₃ / heat	nitrile RCN (1° amide only)	dehydration
DIBAL	aldehyde RCHO (from Weinreb amide R-CO-N(OMe)Me)	low T

From COOH itself (Ch 26)

Reagent	Product
SOCl₂ or (COCl)₂/cat. DMF	acid chloride
ROH + H⁺ (Fischer)	ester (reversible)
DCC or EDC + ROH	ester (Steglich)
DCC or EDC + RNH₂	amide
LiAlH₄	1° alcohol
BH₃	1° alcohol (selective; doesn't reduce ester)
RLi (2 eq)	ketone (1st eq forms carboxylate, 2nd adds once)
Δ + Cu chromite	decarboxylation (β-keto acids easy)

Family 8 — α-Carbon (Enolate) Chemistry

Enolate formation (Ch 27)

Base	Enolate type	Used for
LDA, −78°C, THF	kinetic (less-substituted)	regio control
NaOEt / EtOH, equilibrium	thermodynamic (more-substituted)	regio control
NaH	thermodynamic for active methylene (pKa < 14)	β-dicarbonyl alkylation
KHMDS, LiHMDS, NaHMDS	kinetic for mildly acidic substrates	bulky, non-nucleophilic

α-halogenation

R-CH₂-CO-R' + X₂ → R-CHX-CO-R' (acid) or R-CX₃-CO-R' (base, haloform)

Conditions	Outcome	Ch
acid cat (X₂ / AcOH)	mono α-halo	27
base (X₂ / OH⁻)	polyhalogenation → haloform (CHX₃)	27

α-alkylation

R-CH₂-CO-R' + LDA → enolate + R''X → R-CHR''-CO-R'

Aspect	Detail
Base	LDA (kinetic) or NaH for active methylene
Electrophile	1° R-X best; 2° OK; 3° gives E2
Pitfall	Over-alkylation if proton on α-C remains acidic

Aldol (Ch 28)

R-CH₂-CO-R' + R''CHO → R-C(CO-R')H-CH(OH)R'' (β-hydroxy carbonyl)

Variant	Conditions	Product
Base-catalyzed	NaOH dilute, cold	β-hydroxy ketone
Acid-catalyzed	H⁺, via enol	same
Aldol condensation	OH⁻, warm; or H⁺, warm	α,β-unsaturated carbonyl (E1cb)
Crossed aldol	LDA on one partner first	controlled product
Mukaiyama aldol	silyl enol ether + Lewis acid + aldehyde	controlled, can be asymmetric
Evans aldol	chiral oxazolidinone auxiliary + Bu₂BOTf	asymmetric

Pitfall	Detail
Self-aldol	always possible — control by using non-enolizable acceptor (PhCHO)
Retro-aldol	reversible; thermodynamic product is the condensation alkene

Claisen condensation (Ch 28)

2 R-CH₂-CO-OEt + NaOEt → R-CH(CO-OEt)-CO-CH₂-R + EtOH (β-ketoester)

Aspect	Detail
Base	NaOEt (matched to ester; avoids transesterification)
Substrate	needs 2 α-H's on the donor for product to be deprotonated at end
Intramolecular variant	Dieckmann — diester → cyclic β-ketoester

Michael addition (Ch 29) — 1,4-addition to α,β-unsaturated carbonyl

Nu⁻ + CH₂=CH-CO-R → Nu-CH₂-CH₂-CO-R

Donor	Acceptor	Product
stabilized enolate (β-dicarbonyl)	enone, acrylate	1,4-adduct (kinetic)
Gilman (R₂CuLi)	enone	1,4-adduct
Grignard (RMgX)	enone	1,2-adduct (mainly) — for 1,4, use Cu(I) catalyst
amines	acrylate	β-amino ester
HCN	enone	β-cyano ketone (Stetter for aldehyde acceptor)

1,2 vs 1,4 — hard nucleophiles (RLi, NaBH₄) → 1,2; soft nucleophiles (R₂CuLi, enolate) → 1,4.

Robinson annulation (Ch 29)

Michael + intramolecular aldol → 2-cyclohexenone

Aspect	Detail
Conditions	mild base, sequential or one-pot
Donor	cyclohexanone enolate or β-ketoester
Acceptor	methyl vinyl ketone (MVK)

Mannich reaction (Ch 28)

R-CH=O + R'₂NH + R''-CO-CH₃ → R''-CO-CH₂-CH(R)-NR'₂ (β-aminoketone)

Aspect	Detail
Mechanism	iminium from aldehyde + amine, then enol attack
Pitfall	needs primary or secondary amine; tertiary won't form iminium

Knoevenagel condensation

R-CHO + CH₂(CO₂Et)₂ → R-CH=C(CO₂Et)₂ (piperidine cat.)

Aspect	Detail
Active methylene partners	malonate, acetoacetate, cyanoacetate, nitroalkane
Workup	hydrolysis + decarboxylation → α,β-unsat acid

Stork enamine alkylation

R₂C=O + R'₂NH → enamine (R₂C=CR-NR'₂) + R''X → 2°-alkylated ketone after hydrolysis

Aspect	Detail
Use	clean mono-alkylation without overalkylation
Pitfall	acidify on workup to release ketone

Family 9 — Oxidation and Reduction (Ch 36)

Alcohol oxidations

Reagent	1° alcohol →	2° alcohol →	Notes
Jones (CrO₃/H₂SO₄/acetone)	COOH	ketone	strong, over-oxidizes
PCC (pyridinium chlorochromate)	aldehyde	ketone	mild, stops at aldehyde
PDC (pyridinium dichromate)	aldehyde or COOH (depends)	ketone	—
Swern (DMSO/(COCl)₂/Et₃N)	aldehyde	ketone	very mild, low T
Dess-Martin (DMP)	aldehyde	ketone	mild, neutral, RT
TPAP/NMO	aldehyde	ketone	catalytic Ru
TEMPO/bleach	aldehyde or COOH	ketone	green
MnO₂	allyl/benzyl alcohols only	allyl/benzyl ketones	selective

Ketone/aldehyde reductions

Reagent	Aldehyde →	Ketone →	Ester →	Amide →	Nitrile →	COOH →
NaBH₄	1° OH	2° OH	no	no	no	no
LiAlH₄	1° OH	2° OH	1° OH	amine	1° amine	1° OH
DIBAL-H (1 eq, −78°C)	1° OH (if 2 eq)	2° OH (if 2 eq)	aldehyde	aldehyde	aldehyde	—
BH₃	1° OH	2° OH	slow	—	—	1° OH (selective!)
H₂ / Pd, Pt, Ni	(with C=C reduces too)	(with C=C reduces too)	no	no	1° amine	no
Na/EtOH (Bouveault-Blanc)	1° OH	—	1° OH	—	—	—
Wolff-Kishner (NH₂NH₂, KOH, Δ)	CH₂	CH₂	—	—	—	—
Clemmensen (Zn-Hg, HCl)	CH₂	CH₂	—	—	—	—

Selective alkene/alkyne reductions — see Families 3-4.

Selective oxidative cleavage

Reagent	Cleaves	To
O₃ then Me₂S	C=C	aldehydes/ketones (Ch 16)
KMnO₄ hot	C=C	COOH/ketone
NaIO₄	1,2-diol	two carbonyls (Malaprade)
Pb(OAc)₄	1,2-diol	two carbonyls

Family 10 — Pericyclic Reactions

Diels-Alder [4+2] cycloaddition (Ch 19)

diene (s-cis) + dienophile → cyclohexene (concerted, suprafacial-suprafacial)

Aspect	Detail
Diene	must be s-cis; e.g., cyclopentadiene, butadiene
Dienophile	activated by EWG (-CHO, -CO₂R, -CN, -NO₂); alkene or alkyne
Stereochem	suprafacial on both; endo rule when secondary orbital interactions present
Regiochem	"ortho/para" rule with EDG on diene + EWG on dienophile
Substituent geometry	cis-on-diene → cis-on-product; trans-on-dienophile → trans-on-product (stereospecific)
Catalyst	Lewis acid lowers LUMO of dienophile (AlCl₃, BF₃)
Ch	19

Sigmatropic rearrangements (Ch 39)

Reaction	Description	Conditions
[3,3]-Cope	1,5-hexadiene → 1,5-hexadiene (degenerate or biased)	heat
[3,3]-Claisen	allyl vinyl ether → γ,δ-unsat carbonyl	heat
[3,3]-Aza-Claisen	allyl vinyl amine analog	heat
[3,3]-Ireland-Claisen	silyl ketene acetal of allyl ester	heat after silylation
[2,3]-Wittig	α-alkoxy carbanion with allyl ether	base then heat
[1,5]-H shift	cyclopentadiene H scrambling	heat
[1,3]-shift	rare thermally (forbidden suprafacially)	photochemically

Electrocyclic reactions (Ch 39)

Reaction	π electrons	Thermal mode	Photochemical mode
Butadiene ⇌ cyclobutene	4	conrotatory	disrotatory
Hexatriene ⇌ cyclohexadiene	6	disrotatory	conrotatory
Nazarov (divinyl ketone)	4 (cation)	conrotatory	—

Cycloadditions (Ch 19, 39)

Reaction	[m+n]	Thermal?
Diels-Alder	[4+2]	yes
1,3-dipolar cycloaddition (azide + alkene/alkyne)	[3+2]	yes (Huisgen)
Cu-catalyzed azide-alkyne (CuAAC, "click")	[3+2]	yes, regioselective
[2+2] photochemical	photochem	no thermal
Cheletropic SO₂ + diene	[4+1]	yes
Ene reaction	"[2+2+2]"-like	yes

Family 11 — Functional Group Interconversions (cheat list)

Want	From	How
1° alcohol	aldehyde, COOH, ester	NaBH₄ (ald); LiAlH₄ or BH₃ (acid, ester); H₂ Ni (ester)
2° alcohol	ketone	NaBH₄ or LiAlH₄
Alkyl halide	alcohol	SOCl₂ (Cl), PBr₃ (Br), HX (3°/2° via SN1)
Tosylate	alcohol	TsCl, pyridine
Mesylate	alcohol	MsCl, Et₃N
Aldehyde	1° alcohol	PCC, Swern, DMP
Aldehyde	ester	DIBAL (−78°C)
Ketone	2° alcohol	PCC, Swern, DMP, Jones
COOH	1° alcohol	Jones, KMnO₄
Amine	nitrile	LiAlH₄, H₂/Ni
Amine	amide	LiAlH₄
Amine	nitro (Ar-NO₂)	Sn/HCl, H₂/Pd, Fe/HCl
Nitrile	1° alkyl halide	NaCN, SN2
Acid chloride	COOH	SOCl₂ or (COCl)₂
Anhydride	COOH	(COCl)₂ then COOH; or P₂O₅
Ester	acid chloride + ROH	with base
Amide	acid chloride + RNH₂	Schotten-Baumann
Alkene from alcohol	dehydration	conc H₂SO₄, Δ (E1)
Alkyne from alkene	bromination + double E2	Br₂, then 2 eq NaNH₂
Vicinal diol → carbonyls	cleavage	NaIO₄ or Pb(OAc)₄
Ether from alcohol	Williamson	NaH/RO⁻, then R'X

Protecting groups (Ch 38)

Group	Protects	Install	Remove
TMS, TBS, TIPS, TBDPS	alcohol	RX-Cl + imidazole (or Et₃N)	TBAF, F⁻, dilute acid
Acetal (cyclic)	aldehyde/ketone	HOCH₂CH₂OH, H⁺, −H₂O	aq H⁺
Dithiane	aldehyde/ketone (Corey-Seebach; umpolung!)	HSCH₂CH₂CH₂SH, BF₃	HgCl₂ aq
Bn (benzyl)	alcohol	BnBr, NaH	H₂/Pd hydrogenolysis
MOM (methoxymethyl)	alcohol	MOMCl, i-Pr₂NEt	aq H⁺
THP (tetrahydropyranyl)	alcohol	DHP, H⁺	aq H⁺
Boc	amine	Boc₂O, base	TFA
Cbz	amine	CbzCl, base	H₂/Pd
Fmoc	amine	FmocCl, base	piperidine
Ac (acetate)	amine, alcohol	Ac₂O, pyridine	aq base

Think in families. When you see a new reaction, ask: what family is it? What is the nucleophile, what is the electrophile, what is the leaving group, what controls the stereo and regio outcome? Then look it up here.

Appendix C — Common Reaction Summary (by mechanism family)