Decitabine and Valproic Acid in Treating Patients With Refractory or Relapsed Acute Myeloid Leukemia or Previously Treated Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria:

* Patients with AML (Stratum I) or CLL/SLL (Stratum II) will be enrolled
* Patients in stratum I will have one of the following:

  * Primary refractory or relapsed (in 1 year or less) disease and not a candidate for potentially curative therapy
  * Untreated AML patients who are not candidates for chemotherapy
  * Patients in stratum I must have a normal WBC (=\< 10 x 10\^9/L) or a WBC =\< 40 x 10\^9/L that is stable for 1 week (this may be sustained with hydroxyurea prior to starting therapy and during the first 4 days of therapy if clinically indicated)
* Patients in stratum II will have received at least one prior therapy for CLL/SLL that has included a purine analog; patients in stratum II with a history of severe autoimmune disease or requiring therapy with chronic corticosteroids or who have any other specific relative contraindications to receive a purine analog and, therefore, have received another form of therapy that include alkylating agents will be eligible to participate
* Performance status - ECOG 0-2
* At least 12 weeks life expectancy
* Stratum II:

  * No uncontrolled autoimmune hemolytic anemia
  * No idiopathic thrombocytopenia purpura
* Bilirubin =\< 1.5 mg/dL
* ALT and AST =\< 2 times upper limit of normal
* Creatinine =\< 2.0 mg/dL
* No active infection requiring IV antibiotics
* HIV negative
* No other severe medical condition that would preclude study participation
* No psychiatric condition that would preclude study compliance
* No history of seizures
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception
* More than 14 days since prior chemotherapy (except hydroxyurea)
* No prior FR901228 (depsipeptide) for step 2 of this study
* No other concurrent chemotherapy
* No concurrent corticosteroids for antiemetic therapy
* No concurrent hormonal therapy except for the following:

  * Steroids for treatment of adrenal failure or septic shock
  * Insulin for diabetes
  * Tamoxifen or equivalent for breast cancer prevention or adjuvant therapy
  * Estrogens or progestins for gynecologic indications
* More than 14 days since prior radiotherapy
* No concurrent palliative radiotherapy
* No concurrent anticonvulsant medication, including valproic acid