The Diels-Alder Reaction

M

#

			CF3
	R
OH	O	O B	CF3
OH	O
OH	B	O	H
	O H
OH	O	O
			Ph
	R
65	68	69

		R
	R1	H	DCM, 2,6-t-Bu2Py, Cat.* 66
	+
		O	−40 to −20 C, 16−20 h, 12−87%					CHO
	18
				ee: 88−95%				R1
								R
	R = H, Me, Et, Br;
	R1 = H, Me
				Fe	L	BF4
			(C6F5)2P		P(C6F5)2
			(R, R)			L = CH2=CH-CHO
				66

M

M

	O
R	+	DCM, −78 C		R1	+
		1−24 h.	R
R1			CHO
67	18		endo

CHO

R1

R

exo

$ $
$ $
$ $
$ $
$ $
$ $
$ $
$ $

1

M

M M

M

M

$

	M
H O		O
DCM, Cat.* 69		H
−40 C, 95%, ee 80%		H	! "
			H
70			71

M

M

M

M

	O	SiMe3			DCM, BF3, −10 C, 0.5 h
	+							Me3Si		O
R	H
		SiMe3			41−62%			Me3Si		R	! "
		72
R = Me, Et, i-Pr, i-Bu, Ph
O								OSi-(i-Pr)3		OSi-(i-Pr)	3
			PhMe, BF3 or Me2AlCl
	+							+
R H		OSi-(i-Pr)3			−78 C, 63−94%
						R		O	R	O
		73			O						! "

DMF, CAN

75−95%

R O

R = Me-CH=CH, Ph, Ph-CH=CH, 2-Fu, C6H11, CH2OSPT

M

M

		OMe
	O	R1	CH3CH2CN, Cat.* 76
		+
	R H		−78 C, 4-9 h, 5−92%
		OSMT
			ee 52−97%
	74	R1
		75

R = Ph, 4-MeC6H4, Me-CH=CH, Ph-CH=CH R1 = H, Me, Ph

R2 = substituted phenyl

	O
CF3CO2H	R1		R1
	O		R
Oi-Pr O CO2H O			! "
	O	O
	O
		B
	Oi-Pr	R2
	76

M

"

					O
O	OSMT	(R)-BINOL/Ti(Oi-Pr)4		CF3CO2H
+					H
		DCM, −20 C, 40 h
R H					O R ! "
	OMe	55−88%, ee 92−97%
74

R = Fu, n-C8H17, BnOCH2, TBSOCH2CH2

M

M

						M
Ph	S	CO2Me	Et2O, 25		C, 0.2 h	Ph	S	CO2Me
		+
	Ph						Ph
	77						cis + trans
		Cat.	Yield (%)					! "
		−	68
		ZnCl2	57
		i-PrOAlCl2	75
		AlCl3	77
		EtAlCl2	93

R2	R1	R3	R4		R2	R1	R	R3
	R			DCM, SnCl4, 0 C, 3 h
								R4
		+		15−96%
MeO2C	O	R6	R5		MeO2C	O		R5	! "
							R6
	78					79

R, R1, R2, = H, Me, OMe, Ph; R3, R4, R5, R6 = H, Me, Et, Bu, −(CH2)4−

M

CO2Et					CO2Et		CO2Et
	OR		C, 14 d
+		23				+	! "
		Cat = Fe(BuEtCHCO2)3
O					O OR
		78−80%, de = 98%					O OR
80					major

M

M

R

R

OR1

Cat.*, DCM, −30 to −78

C

+

SO2Ph

6−24 h, 77−92%

PhO2S O

R1O

ee 59−97%

O

81

R = Me, i-Pr, Ph; R1 = Et, i-Pr, i-Bu

! "

Ph

Ph

O

O

X

Cat.* =

X = Cl, Br

Ti

O

O

X

Ph

Ph

R

(MeO)2P

O

OEt

O

82

DCM, −78 C

DCM, −78 C

O

Cat. 83

Cat. 83

R

84−100%

79−100%

R

ee 99%

ee 90−97%

H

(MeO)2P O OEt

(MeO)2P O

O

O

R = Me, i-Pr, OEt, Ph

O

H

OsO4

Sm(OTf)3-MeOH

t-BuOH-H2O

∆, 91%

50%

R

R

HO

R = Me

H

R = Me

HO2C

O

O OEt

O

O

2

O

O

2

O

2X

2X

N N

N

N

Me3C

Cu

Ph

Cu

CMe3

Ph

83a

X = OTf, SbF6

83b

M

M

! "

					O
CO2Me R1	X	DCM, Ln(hfc)3, 20	C	O	CO		Me
						2
+						R1		! "
		56−98%
O O	R2				X
84					R2
X = OR, SR, OSMT	Ln = Eu, Pr

HC	CHR		R
N	N	CHCl3, ZnBr2, 90 C
	+
		2 h, 23−82%
	N		N
	N			! "
86	85		87
R = Ph, Bn, Ph(CH2)2−, Me(CH2)n−		[n = 2, 3, 5, 10]

M

M % # # &

M

# # % # &

! "

M
+	H	C C R	PhH, Co(acac), Et2AlCl
		DIPHOS, 1−24 h, 10−95%						! "
							R
88					89
R = H, Me, Et, i-Pr, Bu, t-Bu, Ph, CH2CH(OAc)CH2CH3,
(CH2)4-OPMB, (CH2)3-OSMDBT

M

M

		O
		( )n
	Ni(COD)	, Ph	P, 80 C, 24 h	H		H
						O
	2	3		( )n
	56% (n = 1), 23% (n = 2)
		SOPh				+
					H
	Ni(COD)2, Ph3P, r.t., 62%, 2 d						SOPh
				SOPh
							H
	88
				exo			endo
						7:1
			O
						+	O
					H
	(CH2Cl)2
				exo			endo
				O
	(Ph3P)2Ni(CO)2, 80 C, 90%					2:1
	Ni(acac)2, Et3Al, 2 Ph3P, r.t., 62%					19:1

			M
	E		E
		Ni(CN)2(PPh3)2
	+		E
		45%
			! "
	E	E = CO2Me
	90		91

M

Co(acac)2, dppe

		Et2AlCl, (3−6 equiv)						( )n
( )n						R
								93
R	n = 1, 2
92
n	1	1	1	1		2	2	2
R	H	Me	TMS	Ph		H	Me	TMS
Yield (%)	78	69	63	70		64	43	48

M

M

M

M

M
O									O	OMe
OMe	+ TiCl4		DCM, −78 C							MeOTiCl4
O											! "
				24 h					O
OMe
94										95
O										O
										OMe
OMe				Cat.
	+									O
O
		DCM, −78 C, 24 h								OMe
OMe
											! "
94		Cat.		Yield (%) para:meta
		TiCl4		66			97:3
	Me3SiOTf 78						>99:< 1

O

O

MeO

94

( )n

H

O O

96

n 1 1 1 1 2 2

+Lewis acid

OMe

		( )n	n = 1, 2
	DCM, −78 C, 24 h
			( )n
+			O
				O
OMe			H	OMe
OMe			97	OMe
Lewis-acid Yield (%) 96:97
TiCl4		85	25:1
Me3SiOTf		41	34:1
BF3 OEt2		21	69:1
GaCl3		84	45:1
TiCl4		89	100:0
Me3SiOTf		83	100:0