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1. A compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein:

V is CH 2 or O;

Y 1 , Y 2 , Y 3 and Y 4 are independently selected from C(R) and N;

each X is independently selected from H and NR 7 R 8 ;

Z 1 and Z 2 are independently selected from the group consisting of

or Z 1 and Z 2 may be joined together with the atoms to which they are attached to form HetB;

L is a linker selected from

(a) a bond,

(b) —CH 2 —,

(c) —C(O)—,

(d) —CH 2 —C(O)-** or —C(O)—CH 2 -**,

(e) —CH 2 —CH 2 —C(O)-** or —C(O)—CH 2 —CH 2 -**, and

wherein ** shows the point of attachment to the morpholine;

R is selected from H, halo, hydroxy, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkyl-S(O) k —, CF 3 , CN, benzyl, or two R groups on adjacent atoms may be joined together with the atoms to which they are attached to form a fused phenyl, pyridine, pyridazine, pyrimidine, pyrazine, or triazine, each of which is optionally substituted with 1 to 4 substituents independently selected from the group consisting of: halo, C 1-4 alkyl, C 1-4 alkoxy, CF 3 and CN;

each k is independently 0, 1 or 2;

each r and t are independently 1, 2, 3 or 4;

Z A is selected from the group consisting of:

(1) hydrogen,

(2) C 1-10 alkyl,

(3) C 2-10 alkenyl,

(4) C 3-7 cycloalkyl,

(5) AryA,

(6) HetA, and

(7) HetB,

wherein said C 1-10 alkyl, C 2-10 alkenyl and C 3-7 cycloalky are optionally substituted with 1 to 6 substituents as allowed by valence independently selected from the group consisting of: fluoro, hydroxy, carbamoyl, C 3-6 cycloalkyl, C(O)O—C 1-6 alkyl, C(O)OH, C(O)—C 1-6 alkyl, N(H)—C 1-6 alkyl, N(—C 1-6 alkyl) 2 , ArylA, HetA and HetB;

each R A is independently H or C 1-6 alkyl;

or Z A and R A and the nitrogen atom to which they are attached may be joined together to form a 5-, 6- or 7-membered mono-cyclic, or 9- or 10-membered bi-cyclic, saturated, aromatic or partially aromatic ring, said ring optionally containing 1 to 3 additional heteroatoms selected from O, S and N, and said ring optionally substituted with from 1 to 3 of X A ;

R 6 is selected from:

wherein the asterisk (*) denotes the point of attachment to the rest of the compound and U 1 is selected from (1) H, (2) C 1-10 alkyl, wherein said C 1-10 alkyl is optionally substituted with 1 to 4 substituents independently selected from halogen, C 1-4 alkyl, C 1-4 haloalkyl, hydroxy and C 1-4 alkoxy, (3) C 3-7 cycloalkyl, wherein said C 3-7 cycloalkyl is optionally substituted with 1 to 4 substituents independently selected from halogen, C 1-4 alkyl, C 1-4 haloalkyl, hydroxy and C 1-4 alkoxy, (4) ArylA, (5) HetA, (6) HetB, (7) C 1-10 alkyl substituted with ArylA, (8) C 1-10 alkyl substituted with HetA, and (9) C 1-10 alkyl substituted with HetB; and Ring B is selected from C 3-7 cycloalky and HetB, wherein C 3-7 cycloalkyl is optionally substituted with 1 to 4 substituents independently selected from halogen, OH, C 1-4 alkyl, C 1-4 fluoroalkyl and C 1-4 alkoxy;

each R 6A independently is H or C 1-6 alkyl;

alternatively, R 6 and R 6A together with the carbon to which they are attached form a C 3-6 cycloalkyl which is optionally substituted with phenyl, wherein the phenyl is optionally substituted with from 1 to 3 of X D ;

each X A , each X B , each X C , each X D , each Y B and each Y C are independently selected from the group consisting of:

(1) C 1-6 alkyl,

(2) C 3-6 cycloalkyl,

(3) C 1-6 haloalkyl,

(4) OH,

(5) O—C 1-6 alkyl,

(6) O—C 1-6 haloalkyl,

(7) O—C 3-6 cycloalkyl,

(8) SH,

(9) S—C 1-6 alkyl,

(10) S—C 1-6 haloalkyl,

(11) S—C 3-6 cycloalkyl,

(12) halo,

(13) CN,

(14) NO 2 ,

(15) NH 2 ,

(16) N(H)—C 1-6 alkyl,

(17) N(—C 1-6 alkyl) 2 ,

(18) N(H)C(O)—C 1-6 alkyl,

(19) N(H)CH(O),

(20) CH(O),

(21) C(O)—C 1-6 alkyl,

(22) C(O)OH,

(23) C(O)O—C 1-6 alkyl,

(24) C(O)NH 2 ,

(25) C(O)N(H)—C 1-6 alkyl,

(26) C(O)N(—C 1-6 alkyl) 2 ,

(27) C(O)N(H)C(O)—C 1-6 alkyl,

(28) C(O)N(H)CH(O)

(29) SO 2 H,

(30) SO 2 —C 1-6 alkyl;

(31) phenyl, benzyl or phenoxy, each optionally substituted with 1 to 5 substituents selected from halogen and C 1-6 alkyl,

(32) HetA, —O-HetA or —CH 2 —HetA, optionally substituted with 1 to 5 substituents selected from halogen and C 1-6 alkyl,

(33) trimethylsilyl, and

(34) C 2-6 alkenyl,

wherein C 1-6 alkyl in each instance of (1), (3) (5), (6), (9), (10), (16), (17), (18), (21), (23), (25), (26), (27), (30), (31) and (32) above is optionally substituted with 1 to 6 substituents as allowed by valence selected from the group consisting of:

(a) C 1-6 haloalkyl,

(b) OH

(c) O—C 1-6 alkyl,

(d) O—C 1-6 haloalkyl,

(e) O—C 3-6 cycloalkyl,

(f) SH,

(g) S—C 1-6 alkyl,

(h) halo,

(i) CN,

(j) NO 2 ,

(k) NH 2 ,

(l) N(H)—C 1-6 alkyl,

(m) N(—C 1-6 alkyl) 2 ,

(n) C(O)—C 1-6 alkyl,

(o) C(O)OH,

(p) C(O)O—C 1-6 alkyl, and

(q) SO 2 —C 1-6 alkyl;

T is O, S, S(O), or SO 2 ;

m is an integer equal to 0, 1, 2, or 3;

n is an integer equal to 0, 1, 2, or 3;

R 7 is H, C 1-6 alkyl, C 3-6 cycloalkyl, C 1-6 alkyl substituted with C 3-6 cycloalkyl, C(O)—R K or SO 2 —R K ;

R 8 is H, C 1-6 alkyl, C 1-6 haloalkyl or C 3-6 cycloalkyl;

R K is:

(1) C 1-6 alkyl,

(2) C 3-6 cycloalkyl,

(3) C 1-6 alkyl substituted with C 3-6 cycloalkyl,

(4) O—C 1-6 alkyl,

(5) O—C 1-6 alkyl substituted with O—C 1-6 alkyl,

(6) O—C 1-6 fluoroalkyl,

(7) C(O)O—C 1-6 alkyl,

(8) C 1-6 alkyl substituted with C(O)O—C 1-6 alkyl,

(9) C 1-6 alkyl substituted with C(O)OH,

(10) C 1-6 alkyl substituted with C(O)—C 1-6 alkyl,

(11) N(H)—C 1-6 alkyl,

(12) N(—C 1-6 alkyl) 2 ,

(13) C 1-6 alkyl substituted with NH 2 , N(H)—C 1-6 alkyl, or N(—C 1-6 alkyl) 2 ,

(14) AryA,

(15) C 1-6 alkyl substituted with AryA,

(16) O—C 1-6 alkyl substituted with AryA,

(17) HetA,

(18) C 1-6 alkyl substituted with HetA,

(19) O—C 1-6 alkyl substituted with HetA,

(20) HetB,

(21) O-HetB, or

(22) O—C 1-6 alkyl substituted with HetB;

each AryA is an aryl which is independently phenyl or naphthyl, wherein the phenyl or naphthyl is optionally substituted with from 1 to 3 Y B ;

each HetA is a heteroaryl which is independently (i) a 5- or 6-membered monocyclic heteroaromatic ring containing from 1 to 4 heteroatoms independently selected from N, O and S, or (ii) is a 9-, 10- or 11-membered bicyclic heteroaromatic ring containing from 1 to 6 heteroatoms independently selected from N, O and S; wherein the monocyclic ring (i) or the bicyclic ring (ii) is optionally substituted with from 1 to 3 Y C ; and

each HetB is independently a 4- to 7-membered, saturated or unsaturated, non-aromatic heterocyclic ring containing at least one carbon atom and from 1 to 4 heteroatoms independently selected from N, O and S, where each S is optionally oxidized to S(O) or S(O) 2 , and wherein the saturated or unsaturated heterocyclic ring is optionally substituted with from 1 to 3 substituents each of which is independently halogen, CN, C 1-6 alkyl, OH, oxo, O—C 1-6 alkyl, C 1-6 haloalkyl, O—C 1-6 haloalkyl, C(O)NH 2 , C(O)N(H)—C 1-6 alkyl, C(O)N(—C 1-6 alkyl) 2 , C(O)H, C(O)—C 1-6 alkyl, CO 2 H, CO 2 —C 1-6 alkyl, SO 2 H, or SO 2 —C 1-6 alkyl.

2. The compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 6 is:

wherein W 1 to W 5 are independently CH or N, with the proviso that no more than three are N, and R 6A is H.

3. The compound according to claim 2 , or a pharmaceutically acceptable salt thereof, wherein Z 1 is C 1-6 alkyl and Z 2 is

and L is —CH 2 —.

4. The compound according to claim 3 , or a pharmaceutically acceptable salt thereof, wherein Z 1 is methyl.

5. The compound according to claim 2 , or a pharmaceutically acceptable salt thereof, wherein Z 1 is

and Z 2 is

wherein L is —CH 2 —.

6. The compound according to claim 2 , or a pharmaceutically acceptable salt thereof, wherein Z 2 is C 1-6 alkyl and Z 1 is

and L is —CH 2 —.

7. The compound according to claim 6 , or a pharmaceutically acceptable salt thereof, wherein Z 2 is methyl.

8. The compound according to claim 7 , or a pharmaceutically acceptable salt thereof, wherein Z 1 is

9. The compound according to claim 1 of Formula Ia

or a pharmaceutically acceptable salt thereof, wherein W 1 is CH or N.

10. The compound according to claim 9 , or a pharmaceutically acceptable salt thereof, wherein:

Z 2 is methyl

R is H or fluoro,

Y 3 is CH or N,

X B and X C are independently selected from F, Cl, Br, —OCH 3 , —CF 3 and —OCF 3 , and m and n are independently 0, 1 or 2.

11. The compound according to claim 10 , or a pharmaceutically acceptable salt thereof, wherein X is selected from: H, —NH 2 and —N(H)—C(O)—R K wherein R K is O—C 1-6 alkyl or O—C 1-6 fluoroalkyl.

12. The compound according to claim 11 , or a pharmaceutically acceptable salt thereof, wherein W 1 is CH, one X B group is present and substituted at the 4-position, one or two X C groups are present and substituted at the 3- or 3,5-positions respectively, and the X B group is a different group with respect to either X C group.

13. The compound according to claim 10 , or a pharmaceutically acceptable salt thereof, wherein Z A is selected from the group consisting of:

(1) hydrogen,

(2) C 1-10 alkyl,

(3) C 2-10 alkenyl, and

(4) C 3-7 cycloalkyl,

wherein said C 1-10 alkyl, C 2-10 alkenyl and C 3-7 cycloalky are optionally substituted with 1 to 6 substituents as allowed by valence independently selected from the group consisting of: fluoro, hydroxy, carbamoyl, C 3-6 cycloalkyl, C(O)O—C 1-6 alkyl, C(O)OH, C(O)—C 1-6 alkyl, N(H)—C 1-6 alkyl, N(—C 1-6 alkyl) 2 , ArylA, HetA and HetB.

14. The compound according to claim 13 , or a pharmaceutically acceptable salt thereof, wherein Z A is C 1-10 alkyl, optionally substituted with 1 to 6 substituents as allowed by valence independently selected from the group consisting of: fluoro and hydroxy.

15. The compound according to claim 14 , or a pharmaceutically acceptable salt thereof, wherein Z A is —(CH 2 ) 0-4 —CF 3 .

16. A compound selected from the group consisting of:

N-(2-{2-[(2R,5R,6S)-6-{[(4-chlorophenyl)sulfanyl]methyl}-5-methylmorpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-6-{[(4-cyanophenyl)sulfanyl]methyl}-5-methylmorpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-6-{[(3-chloropyridin-2-yl)sulfanyl]methyl}-5-methylmorpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

methyl [(2S)-1-{[2-(2-{(2R,5R,6S)-5-methyl-6-[(quinolin-5-ylsulfanyl)methyl]morpholin-2-yl}ethyl)phenyl]amino}-1-oxo-3,3-diphenylpropan-2-yl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[5-(4-pyridyl)-1,3,4-oxadiazol-2-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[5-[(5-methylpyrazol-1-yl)methyl]-1,3,4-oxadiazol-2-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[5-[(2-methylthiazol-4-yl)methyl]-1,3,4-oxadiazol-2-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[(5-chloro-2-pyridyl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-(quinoxalin-2-ylsulfanylmethyl)morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-(1H-pyrazolo[3,4-d]pyrimidin-4-ylsulfanylmethyl)morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[(1-methylpyrazolo[3,4-d]pyrimidin-4-yl)sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[(3,4-dimethylphenyl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-(1,3,4-thiadiazol-2-ylsulfanylmethyl)morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[2-(trifluoromethyl)quinazolin-4-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[[5-[1-hydroxy-1-(trifluoromethyl)propyl]thiazol-2-yl]sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[(4,5-dimethyloxazol-2-yl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[[5-(difluoromethoxy)-1H-benzimidazol-2-yl]sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6 S)-5-methyl-6-[[4-methyl-6-(trifluoromethyl)pyrimidin-2-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-(4-pyridyl sulfanylmethyl)morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[3-(trifluoromethyl)-2-pyridyl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[(5-chlorothiazolo[5,4-b]pyridin-2-yl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-(1H-imidazo[4,5-b]pyridin-2-ylsulfanylmethyl)-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[[9-[(2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl]purin-6-yl]sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-(1H-1,2,4-triazol-3-ylsulfanylmethyl)morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-[[2-[2-[(2R,5R,6S)-6-[(4-amino-1H-pyrazolo[3,4-d]pyrimidin-6-yl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]carbamoyl]-2,2-diphenyl-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-5-methyl-6-[[5-(pyrrolidin-1-ylmethyl)-1,3,4-oxadiazol-2-yl]sulfanylmethyl]morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[(3-cyano-4,6-dimethyl-2-pyridyl)sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-[[1-(2-dimethylaminoethyl)tetrazol-5-yl]sulfanylmethyl]-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

methyl N-[(1S)-1-benzhydryl-2-[[2[2-[(2R,5R,6S)-6-(1H-imidazol-2-ylsulfanylmethyl)-5-methyl-morpholin-2-yl]ethyl]phenyl]amino]-2-oxo-ethyl]carbamate;

[(2S,3R,6R)-6-[2-(2-{[N-(methoxycarbonyl)-β-phenyl-L-phenylalanyl]amino phenyl)ethyl]-2-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)morpholin-3-yl]methyl acetate;

N-(2-{2-[(2R,5R,6S)-5-(hydroxymethyl)-6-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-5-(1H-imidazol-2-yl)-6-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-5-(1H-imidazol-2-yl)-6-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

Nα-(methoxycarbonyl)-β-phenyl-N-(2-{2-[(2R,5R,6S)-6-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl methyl)-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy methyl)morpholin-2-yl]ethyl}phenyl)-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-5-({[(4-fluorobenzyl)carbamoyl]oxy}methyl)-6-({[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)morpholin-2-yl]ethyl phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-[2-(2-{(2R,5R,6S)-5-[(carbamoyloxy)methyl]-6-methylmorpholin-2-yl}ethyl)-3-fluorophenyl]-4-fluoro-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-[3-fluoro-2-(2-{(2R,5R,6S)-6-methyl-5-[({[(1S)-2,2,2-trifluoro-1-methylethyl]carbamoyl}oxy)methyl]morpholin-2-yl ethyl)phenyl]-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-[3-fluoro-2-(2-{(2R,5R,6S)-5-[({[(1R)-1-(4-fluorophenyl)propyl]carbamoyl oxy)methyl]-6-methylmorpholin-2-yl}ethyl)phenyl]-β-(4-fluorophenyl)-L-phenylalaninamide;

Nα-(methoxycarbonyl)-N-(2-{2-[(2R,5R,6S)-5-methyl-6-({[6-(4-methylpiperazin-1-yl)pyrimidin-4-yl]sulfanyl}methyl)morpholin-2-yl]ethyl}phenyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6 S)-6-{[(4-chlorophenyl)sulfonyl]methyl}-5-methylmorpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-6-{[(R)-(4-chlorophenyl)sulfonyl]methyl-5-methylmorpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6 S)-5-[(benzyloxy)methyl]-6-(hydroxymethyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

Nα-(methoxycarbonyl)-β-phenyl-N-(2-{2-[(2R,5R,6S)-6-{[(5-pyridin-4-yl-1,3,4-oxadiazol-2-yl)sulfanyl]methyl}-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-6-{[(4-chlorobenzyl)oxy]methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

4-fluoro-N-(5-fluoro-4-{2-[(2R,5R,6R)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl pyridin-3-yl)-β-(4-fluorophenyl)-L-phenylalaninamide;

N-(2-{2-[(2R,5R,6S)-6-(hydroxymethyl)-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy methyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6R)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-2-[(2R,5R,6R)-5-({[(4-fluorobenzyl)carbamoyl]oxy}methyl)-6-methylmorpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6S)-5-(hydroxymethyl)-6-methylmorpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6S)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(5-fluoro-4-{[(2S,5R,6R)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]methoxy}pyridin-3-yl)-β-(4-fluorophenyl)-L-phenylalaninamide;

N-[4-({(2S,5R,6R)-5-[(carbamoyloxy)methyl]-6-methylmorpholin-2-yl}methoxy)-5-fluoropyridin-3-yl]-4-fluoro-β-(4-fluorophenyl)-L-phenylalaninamide;

N-[4-(2-{(2R,5R,6S)-5-[(carbamoyloxy)methyl]-6-methylmorpholin-2-yl}ethyl)-5-fluoropyridin-3-yl]-4-fluoro-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(5-fluoro-4-{2-[(2R,5R,6S)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}pyridin-3-yl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6R)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6R)-5-({[(4-fluorobenzyl)carbamoyl]oxy}methyl)-6-methylmorpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-(5-fluoro-4-{2-[(2R,5R,6R)-6-methyl-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}pyridin-3-yl)-β-(4-fluorophenyl)-L-phenylalaninamide;

4-fluoro-N-[3-fluoro-2-(2-{(2R,5R,6S)-5-[({[(1R)-1-(4-fluorophenyl)-2-methylpropyl]carbamoyl}oxy)methyl]-6-methylmorpholin-2-yl}ethyl)phenyl]-β-(4-fluorophenyl)-L-phenylalaninamide;

N-[2-(2-(2R,5R,6 S)-5-[({[(R)-cyclopropyl(4-fluorophenyl)methyl]carbamoyl oxy)methyl]-6-methylmorpholin-2-yl}ethyl)-3-fluorophenyl]-4-fluoro-β-(4-fluorophenyl)-L-phenylalaninamide;

N-{3-fluoro-2-[(2S,4aR,9aS)-2,3,4,4a,9,9a-hexahydroindeno[2,1-b][1,4]oxazin-2-ylmethoxy]phenyl}-β-phenyl-L-phenylalaninamide;

4-fluoro-N-[3-fluoro-2-(2-{(2R,5R,6S)-6-methyl-5-[({[(1R)-2,2,2-trifluoro-1-methylethyl]carbamoyl}oxy)methyl]morpholin-2-yl}ethyl)phenyl]-β-(4-fluorophenyl)-L-phenylalaninamide;

[(2S,3R,6R)-6-[2-(2-{[3,3-bis(4-fluorophenyl)propanoyl]amino}-6-fluorophenyl)ethyl]-3-(hydroxymethyl)morpholin-2-yl]methyl (2,2,2-trifluoroethyl)carbamate;

4-fluoro-N-(3-fluoro-2-{2-[(2R,5R,6S)-5-(hydroxymethyl)-6-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-β-(4-fluorophenyl)-L-phenylalaninamide; and

N-(2-{2-[(2R,5R,6 S)-6-[(4-cyanophenoxy)methyl]-5-({[(2,2,2-trifluoroethyl)carbamoyl]oxy}methyl)morpholin-2-yl]ethyl}phenyl)-Nα-(methoxycarbonyl)-β-phenyl-L-phenylalaninamide;

and pharmaceutically acceptable salts thereof.

17. A pharmaceutical composition comprising an effective amount of a compound according to claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

18. A method for the treatment of infection by HIV or for the treatment, prophylaxis or delay in the onset of AIDS in a subject in need thereof, which comprises administering to the subject an effective amount of the compound according claim 1 or a pharmaceutically acceptable salt thereof.

19. A pharmaceutical composition comprising an effective amount of a compound according to claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier and further comprising an effective amount of an anti-HIV agent selected from the group consisting of HIV antiviral agents, immunomodulators, and anti-infective agents.

20. The pharmaceutical composition of claim 19 , wherein the anti-HIV agent is an antiviral selected from the group consisting of HIV protease inhibitors, HIV reverse transcriptase inhibitors, HIV integrase inhibitors, HIV fusion inhibitors, HIV entry inhibitors, and HIV maturation inhibitors.