A is selected from —R¹—(C₁-C₆)-alkyl, which is optionally substituted with one or more groups independently selected from hydroxy, C₁-C₄ alkoxy, Ht, —O-Ht, —NR²—CO—N(R²)₂ or —CO—N(R²)₂; —R¹—(C₂-C₆)-alkenyl, which is optionally substituted with one or more groups independently selected from hydroxy, C₁-C₄ alkoxy, Ht, —O-Ht, —N(R²)—C(O)—N(R²)₂ or —CO—N(R²)₂; or R⁷;

each R¹ is independently selected from —C(O)—, —S(O)₂—, —C(O)—C(O)—, —O—C(O)—, —O—S(O)₂, —N(R²)—S(O)₂—, —N(R²)—C(O)— or —N(R²)—C(O)—C(O)—;

each Ht is independently selected from C₃-C₇ cycloalkyl; C₅-C₇ cycloalkenyl; C₆-C₁₀ aryl; or a 5-7 membered saturated or unsaturated heterocycle, containing one or more heteroatoms selected from N, N(R²), O, S and S(O)_n; wherein said aryl or said heterocycle is optionally fused to Q; and wherein any member of said Ht is optionally substituted with one or more substituents independently selected from oxo, —OR², SR², —R², —N(R²)₂, —R²—OH, —CN, —C(O)O—R², —C(O)—N(R²)₂, —S(O)₂—N(R²)₂, —N(R²)—C(O)—R², —C(O)—R², —S(O)_n—R², —OCF₃, —S(O)_n-Q, methylenedioxy, —N(R²)—S(O)₂—R², halo, —CF₃, —NO₂, Q, —OQ, —OR⁷, —SR⁷, —R⁷, —N(R²)(R⁷) or —N(R⁷)₂;

each R² is independently selected from H, or (C₁-C₄)-alkyl optionally substituted with Q;

B, when present, is —N(R²)—C(R³)₂—C(O)—;

each x is independently 0 or 1;

each R³ is independently selected from H, Ht, (C₁-C₆)-alkyl, (C₂-C₆)-alkenyl, (C₃-C₆)-cycloalkyl or (C₅-C₆)-cycloalkenyl; wherein any member of said R³, except H, is optionally substituted with one or more substituents selected from —OR², —C(O)—NH—R², —S(O)_n—N(R²)₂, Ht, —CN, —SR², —CO₂R², N(R²)—C(O)—R²;

each n is independently 1 or 2;

G, when present, is selected from H, R⁷ or (C₁-C₄)-alkyl, or, when G is (C₁-C₄)-alkyl, G and R⁷ are bound to one another either directly or through a C₁-C₃ linker to form a heterocyclic ring; or when G is absent, the atom to which G is attached is bound directly to the R⁷ group in —OR⁷ with the concomitant displacement of one -ZM group from R⁷;

D and D′ are independently selected from Q; (C₁-C₆)-alkyl; (C₂-C₄)-alkenyl; (C₃-C₆)-cycloalkyl, which is optionally substituted with or fused to Q; or (C₅-C₆)-cycloalkenyl, which is optionally substituted with or fused to Q;

each Q is independently selected from a 3-7 membered saturated, partially saturated or unsaturated carbocyclic ring system; or a 5-7 membered saturated, partially saturated or unsaturated heterocyclic ring containing one or more heteroatoms selected from O, N, S, S(O)_n or N(R²); wherein any ring in Q is optionally substituted with one or more groups selected from oxo,

E is selected from Ht; O-Ht; Ht-Ht; —O—R³; —N(R²) (R³); (C₁-C₆)-alkyl, which is optionally substituted with one or more groups selected from R⁴ or Ht; (C₂-C₆)-alkenyl, which is optionally substituted with one or more groups selected from R⁴ or Ht; (C₃-C₆)-saturated carbocycle, which is optionally substituted with one or more groups selected from R⁴ or Ht; or (C₅-C₆)-unsaturated carbocycle, which is optionally substituted with one or more groups selected from R⁴ or Ht;

each R⁴ is independently selected from —OR², —SR², —C(O)—NHR², —S(O)₂—NHR², halo, —N(R²)—C(O)—R², —N(R²)₂ or —CN;

each R⁷ is independently selected from

wherein each M is independently selected from H, Li, Na, K, Mg, Ca, Ba, —N(R²)₄, (C₁-C₁₂)-alkyl, (C₂-C₁₂)-alkenyl, or —R⁶; wherein 1 to 4 —CH₂ radicals of the alkyl or alkenyl group, other than the —CH₂ that is bound to Z, is optionally replaced by a heteroatom group selected from O, S, S(O), S(O)₂, or N(R²); and wherein any hydrogen in said alkyl, alkenyl or R⁶ is optionally replaced with a substituent selected from oxo, —OR², —R², N(R²)₂, N(R²)₃, R²OH, —CN, —C(O)OR², —C(O)—N(R²)₂, S(O)₂—N(R²)₂, N(R²)—C(O)—R₂, C(O)R², —S(O)_n—R², OCF₃, —S(O)_n—R⁶, N(R²)—S(O)₂—R², halo, —CF₃, or —NO₂;

M′ is H, (C₁-C₁₂)-alkyl, (C₂-C₁₂)-alkenyl, or —R⁶; wherein 1 to 4 —CH₂ radicals of the alkyl or alkenyl group is optionally replaced by a heteroatom group selected from O, S, S(O), S(O)₂, or N(R²); and wherein any hydrogen in said alkyl, alkenyl or R⁶ is optionally replaced with a substituent selected from oxo, —OR², —R², —N(R²)₂, N(R²)₃, —R²OH, —CN, —CO₂R², —C(O)—N(R²)₂, —S(O)₂—N(R²)₂, —N(R²)—C(O)—R₂, —C(O)R², —S(O)_n—R², —OCF₃, —S(O)_n—R⁶, —N(R²)—S(O)₂—R², halo, —CF₃, or —NO₂;

Z is CH₃, O, S, N(R²)₂, or, when M is not present, H;

Y is P or S;

X is O or S; and

R⁹ is C(R²)₂, O or N(R²); and wherein when Y is S, Z is not S; and

R⁶ is a 5-6 membered saturated, partially saturated or unsaturated carbocyclic or heterocyclic ring system, or an 8-10 membered saturated, partially saturated or unsaturated bicyclic ring system; wherein any of said heterocyclic ring systems contains one or more heteroatoms selected from O, N, S, S(O)_n or N(R²); and wherein any of said ring systems optionally contains 1 to 4 substituents independently selected from OH, C₁-C₄ alkyl, O—(C₁-C₄)-alkyl or O—C(O)—(C₁-C₄)-alkyl.