The Diels-Alder Reaction

M

! " ! "

! " ! " M

OMe

H

H

O

, SmI2

O

, SmI2

H ! "

25 C, 24 h, 92%

−30 C, 2 h, 80%

CO2Me

18

O

C

H

endo/exo = 9:1

endo/exo = 4:1

OMe

OMe

O

DCM, SmI2

O

TFA

O

+

−30 C, 80−98%

R! "

R H

TMSO

R

O

OSMT

R = Ph, Ph-CH=CH-, 2-Fu

M

M

	R			R			CO2Me R
CO2Me+			Solv., Cat.
							+
t-BuO2C		−78 to −20 C, 1−72 h					CO2t-Bu

CO2t-Bu

CO2Me

30				A		B
	R	Catalyst	Solvent	A/B
	Me	−	PhMe	56:44
		Et2AlCl	DCM	44:56
		MAD	DCM	14:86
		MAD	PhMe	20:80
	OSiMe3	−	PhMe	48:52
		Et2AlCl	DCM	44:56
		MAD	DCM	1:99
		MAD	PhMe	17:83

	OR* +		DCM, CatT.		+	H +	+	CO2R*
		−78 to −20 C
	O				H	CO2R*	CO2R*	H
					CO2R*		H
	31	18			A	B	C
			Cat. (equiv.)		endo/exo	A/B	Yield (%)
			TiCl4 (1)		97:3	97:3	83
	R* =		SnCl4 (2)		97:3	97:3	97
	O O		EtAlCl2 (2)		99:1	86:14	97
			MAD (2)		95:5	5:95	96
			MABR (2)		89:11	5:95	97

	R4							R1
R3							R2	CO2Me
	R
		MeO2C	CO2Me	CuCl-LiCl
	Zr +
				r.t., 54−71%
	R							CO2Me ! "
R2							R3
	R1
								R4
	32

R = Ph; R1, R2, R3, R4 = Me, Et, Bu, Ph, SiMe3

				M
Et							Et
			CuCl-LiCl			Et
Et	+ MeO2C	CO2Me
							! "
Ph Zr	Ph	54%				MeO2C
							CO2Me
	33

$ $ $ $ $

		R1 R2		R1	R2
R	R4O	R3	MeAlCl2	O	O
			4-99%
				R	H	! "
		O		R4 R3 O
		34		35	36

R, R1, R2, R3, R4 = H, Me

M

	BnOH2C	BnO		O
OR*		DCM, TiCl4	R* =
	+			O	! "
O		−15 C, 79%
		de 94%	CO2R*
37			38

M

M

	O		TiCl4, DCM, −78 C R		SOTol
	S CO2Bn	R					R	CO2Bn
						r.t.
	Tol	+			CO2Bn			CO2Me ! "
			66−91%, ee 83−96% R1
	CO2Me	R1			CO2Me		R1
	39	R, R1 = H, Me, OMe

	O				O	O
	S	CO2Me	DCM, LiClO4 R		S	S
		+			+	R
R*			25 C, 7h, 70%,				CO2Me
					CO2Me
			d.e.: 96:4
		OMe			OMe	OMe	! "

40

HO

R* =

BnO

O

CO2Men

BnO

O

O

DCM, Et2AlCl

BnO

+

BnO

CO2Men

Py

−20

C, 5d, 79% BnO

S

CO2Men BnO

SOPy

O

SOPy

44

41

43

! "

O DCM, Et2AlCl

Men = (−)menthyl

O

Py = 2-pyridyl

CO2Men

SOPy

42

				M
R	R		R	R
	R	R R		R
	R R			R = OAc
R	R	NHR		R R
	45	46		47

		O
Fe	PF6	O	B Br	[Ru(salen)(NO)(H2O)] SbF6
48		49		50

M
[Zr(Cp)2(CF3SO3)2THF]	[Ti(Cp)2(CF3SO3)2]
51	52

M

CHO	R	1			R1	R
	+			DCM, Cat. 53
R			−78 C to r.t., 24 h, 60−97% R2			CHO	! "
	R2
R = H, Me	R1, R2 = H, Me

M

M

			O
		H	N
P			O
		OBn	O
		N	SO2
Fe	OTf		Al CF3
		N	Me
OC O CO

	SO2
53	CF3
	55

M

M

M

	OBn	O			BnO
	+	N O	DCM, Cat.* 54 (Ar = Ph)
						O
			−78	C, 18 h, 93%, ee = 94%
		O			O	N O

! "

Ar Ar

Cat.* =F3CO2S N Al N SO2CF3

54

O		H	O
N Ar1 +	C7H8, −78 C, Cat.* 54		N Ar1
OMe		MeO
O		H	O

56
Ar (54) Ar1 (56)		(ee %)
Ph	Ph	35
Ph o-MeC6H4		58
Ph o-t-Bu-C6H4		52

Ar (54)	Ar1 (56)	(ee %)
3,5-Me2C6H3	Ph	62
3,5-Me2C6H3	o-MeC6H4	93
3,5-Me2C6H3	o-t-Bu-C6H4	95

M

$

		OMe
		O
a	b		N
O
	Me
O	H	SO2	O	R
	Me	N
			CF3
O	N	Al
		Me
	H	SO2
	Me
		CF3
	Me
		57

M

#

	CO2Me	DCM, Cat.* 58, 0 C, 9 h		+
	+
		35−83%, ee = 36−77%
				CO2Me
	18			CO2Me
	SiAr3			! "
	O
	Al	Me Ar3 = Ph3, (t-Bu,2 Ph), (4-t-BuC6H4)3, (3,5-Et2C6H3)3
	O

SiAr3

58

		M
O	Br	O	Br
B	Ar	B	Br
N	Br	N	Ar
	Ar		Ar
59		59a

# % ! " &

O
R		Cat.* 59 B[C6H3−3,5(CF3)2]4				CHO
+	H
		DCM, −94 C, 2 h, 97−99%			R		! "
R1
					R1
18
R = Br, Me; R1, = H, Me					exo:endo = 88−98:12−2
O						Br
Br			Cat.* 59 B[C6H3−3,5(CF3)2]4
	+					CHO	! "
H
			DCM, −94 C, 0.5−2 h

99%; ee 93−98%

		R1		O
			O
				N O
Cat.* 61, PhMe,		R = H, R1 = H, Me R		R = Me, Ph		Cat.* 62
				60		DCM, 0 C, 10 h
0 C-r.t., 12−48 h
						83−89%
81−93%
R1						R
		O				O
C		N O		O	C
O						N O
ee 93−96%				ee (endo) 92−97%

	M
		Ph	N
	Ph		H
	Ph O
		O	O
	O	TiCl2	Sc(OTf)3
		O	O
	Ph	Ph	H
	61		N

62

			O
			Ph
	O Me Ti			O
	O		O O
R
		N	O
			63
Ph	Ph
Ph O	OH
R		+	TiCl2(Oi-Pr)2
R
	OH
O
Ph	Ph

O

Ph

OMe TiO O O O

O N R

64

Ph Ph

Ph O O

O	TiCl2	+ 2 i-PrOH
	O	! "
Ph	Ph

61